The Restoration of Enigma A16878

Restoration of Enigma A16878 – Part 1

(Scroll down for Parts 2 & 3)

May 2018

Over the next year, we will be documenting the restoration of the 3-rotor Enigma machine with serial number A16878. In part 1 we will review the known history of this Enigma machine, evaluate the machine’s external condition, and make an initial assessment of what will be needed for the restoration process.8


1. History

Enigma A16878 was found in 2017 by a man in Antwerp Belgium who came across the machine while cleaning out an old storage shed. There were no other related items located in the shed. The ID tag located in front of the keyboard reads “A” and “16787 / jla / 43”. The presence of this ID tag is very helpful. This tells us that the machine was made in Berlin in 1943 by Heimsoeth und Rinke which was located at Uhlandstr. 136, Berlin-Wilmersdorf. Many surviving Enigma machines either were not issued with an ID tag or the ID tags have been lost to time. As with nearly all surviving Enigma machines, there are no surviving documents to verify where this machine saw service during WWII. This model Enigma, the Enigma I, saw service with the Wehrmacht and Luftwaffe, as well as many branches of the German government. During WWII, Antwerp was an important city because of its deep water port. It was occupied by Germany in May 1940 and liberated by the British 11th Armored Division in September 1944. As mentioned above, we cannot verify that Enigma A16787 saw service in Antwerp during the war.

2. Condition

  • There is no transport box with the machine.
  • One of the four transport box mounting screws is present and screwed into the underside of the machine. The other three mounting screws are missing.
  • The machine is missing the Steckerboard (plugboard).
  • The wire trunks that connect the sockets of the Steckerboard to the electrical circuit of the machine have been intentionally cut. We can only speculate that one reason the Steckerboard may be missing is that the Germans intentionally disabled or destroyed Enigma machines rather then let them be captured by the Allies at the end of the war. We have seen at least one other example of an Enigma machine being intentionally disabled in this manner.
  • There are no Stecker cables present.
  • Based on the amount of corrosion on the machine, one could speculate that the wooden box rotted away from this machine over time.
  • There are no lightbulbs present.
  • There is rust and corrosion on the exterior and interior of the machine on nearly all exposed metal surfaces.
  • There is a thin layer of dirt and dust on the exterior and throughout the interior of the machine.
  • There appear to be dried pine needles inside the Enigma below the rotors.
  • The mechanism to release the rotors is stiff and binding; however, it was possible to remove the rotors from the machine.
  • The “M” key glass is broken, and the “I” key glass has a small fracture.
  • When keys are pressed, there is resistance and the keys do not return to their starting position. The rotors do not advance when a key is pressed.
  • The clips for the rotor cover and contrast screen on the top of the machine are rusted in place and are not able to be moved.
  • Both cover hold-down screws on the top of the machine are bent and one is seized in place.
  • Rotors I, II, and III are present and all are engraved with the same serial number as the machine, A16787. The rotors appear to be original to the machine and in good condition.
  • It is not clear if this machine was located in a high-moisture environment and/or was submerged in water at some point in the past 75 years. If the machine was submerged, it may have been for a relatively short period of time based on the degree of corrosion compared to other water-damaged machines we have seen in the past.

3. Initial Assessment of Restoration Process

  • A thorough disassembly and cleaning of every piece of this machine will be required.1
  • Many parts will require soaking with penetrating oil to access for service.
  • A replacement Steckerboard will have to be assembled, wired, and connected to the machine.
  • Stecker cables will have to be located for this machine.
  • Keyboard keys will need to be repaired.
  • All electrical contacts will have to be cleaned and tested.
  • The rotor contacts will have to be cleaned and tested. Testing will include verification that the wiring of each rotor is consistent with Enigma I rotors.
  • Certain parts will require light lubrication after being cleaned or repaired.
  • An appropriate transport box will have to be acquired for this machine.
  • Lightbulbs will have to be placed in the machine.
  • A battery pack will be placed in the machine to allow it to be fully functional.
  • Final testing of all electrical and mechanical elements will be required.
  • Enigma A16878 will be photographed and added to the Enigma Museum archives.

Notes: This assessment may change as the machine is dismantled and the interior is inspected more closely.

Part II will include the removal of the metal top and sides of the Enigma machine so that the interior of the machine can be examined. All screws will have to be pretreated with penetrating oil to ensure that they are not damaged when removed. Disassembly of the machine will begin.

End of Part I

See pictures below. (The last picture is of this Enigma machine’s new home while it is being restored.)





























































































































Restoration of Enigma A16878 – Part 2

June 2018

In Part 2 of the restoration, we will remove the outer metal case from the Enigma machine and inspect the machine for any damage or missing parts not identified in Part 1. Then we will remove the various components from the base of the machine to allow for better access to all parts of the machine for cleaning and repairs as needed. Throughout this process we will be using small amounts of penetrating oil and great care in removing parts so as not to damage screws or other fasteners that may have corroded in place. Only small amounts of penetrating oil are used to avoid damaging the finish of the machine and limiting the chance that oil will contaminate electrical contacts.


  1. Remove metal case and top from the machine. This is done by removing screws from around the base of the machine as well as very small screws located in hinged area of the metal cover in the back of the machine.












With the cover removed, we can see confirmation of our original assessment that there is corrosion on almost all exposed metal parts of the machine. In addition, we see that there is dirt, small glass fragments from broken light bulbs, and a few pine needles scattered around inside the machine. The presence of broken light bulbs is not uncommon on machines that we inspect. However, we have not previously encountered pine needles in an Enigma machine! To keep the “story” of this machine alive, we will save some of the pine needles and other debris from this machine in a clear plastic bag to accompany the machine when it is fully restored.












  1. Remove keyboard assembly. The removal of the keyboard assembly is standard practice for us when cleaning an Enigma machine and restoring it back to working order. The electrical contacts that are activated when the keys are pressed are prone to corrosion and often require cleaning regardless of the overall condition of the machine. In the case of this machine, not only are the key contacts heavily corroded, but so too are the actual key tops and stems. The keys are difficult to press and do not return to their starting position due to this corrosion. The keys will have to be removed from the keyboard assembly and cleaned individually.










  1. Remove the Lamp panel and the keyboard contact assembly. First the lamp panel is removed from the machine. Then screws are removed from under the base plate to allow for the removal of the keyboard contact assembly.













  1. Remove the battery holder. The battery holder is removed to allow access to the nuts that secure the input rotor to the machine.











  1. Remove the input rotor. Extra care is taken any time we work with components containing Bakelite parts such as the input rotor. 75 year old Bakelite is fragile and easily broken.

As previously observed, this Enigma machine is missing the Steckerboard (plugboard). Normally, wires would come out of the keyboard contacts to the Steckerboard and then from the Steckerboard to the input rotor. The whole electrical assembly of the machine would be connected via wire trunks. Locating, assembling, and wiring a Steckerboard will be a later step in this restoration process.

  1. Removal of the stepping bar. The stepping bar is removed to allow nearly full access to the base for a thorough inspection and cleaning.



  1. Apply penetrating oil to corroded clips and fasteners on metal top of Enigma.



End of Part 2.

Part 3 of the restoration process for this Enigma machine will involve cleaning the various components of the machine.



Restoration of Enigma A16878 – Part 3

November 2018

In part 3 of this restoration we will be testing circuits and identifying wires. In addition, we will clean the key contacts, light bulb contacts, rotor advance pawls, and letter film.

  1. The input wheel, or Entrittswalze, had its wires cut, likely when this Enigma machine was intentionally disabled by its operator at the end of the war. Using an electric meter, we test the functionality of the input wheel and identify the 26 wires in the wire bundle. Once identified, the wires are labeled A-Z with colored tabs.








2. All interior and exterior components of Enigma A16878 show signs of exposure to moisture and dust. Corrosion is present on nearly all exposed metal parts. The keyboard contacts need to be quite clean to ensure good functionality of the machine. We sometimes use tamarind paste (an acid) in water as a gentle cleanser to remove rust and corrosion. For cleaning the metal contacts we are using 1200 grit sandpaper. We are not applying a lot of pressure with the sandpaper so as not to damage the contacts. Normally, we would use a less abrasive cleaning medium; however, the corrosion on this machine is extensive.











3. The light bulb contacts on this machine had a coating of dirt and corrosion. With the light bulb socket panel removed we can access the contacts with a brass rotary brush.











4. Once the light bulb and key contacts are cleaned and reassembled, we use a circuit tester to identify and label the wires A-Z. The wire trunk was intentionally cut at some point in the 75-year history of this machine so we are also splicing on additional wire that will be able to reach around the light bulb and keyboard assembly to the plug board on the front of the machine.



5. It appears that Enigma A16878 was stored for a long period of time in a dusty and moist environment without a wooden box, or panzerholz case. One result of this is a significant buildup of dust and dirt on the letter film. We used a solution of warm water with a small amount of dish detergent for cleaning.












6. On many of the Enigma machines we service, the springs holding back the stepping pawls are corroded and fail to press the pawls against the rotors. This results in the rotors failing to advance with key presses. We have found that in most cases the springs either rust and/or the lubrication oil has become firm with age. The fix for the springs is a combination of lubricating oil and moving the pawls manually to work the oil into the mechanism. In severe cases, a soldering iron can be held to the spring to assist the effectiveness of the penetrating oil. Caution should be taken not to get excess oil spread throughout the machine. The oil can cause rotor connections and other electrical contacts to become nonfunctional.












End of Part 3

Parts 4 and 5 will likely include the dismantling and cleaning of the keyboard and the construction of a plug board or Steckerbrett from replica and original parts. The Steckerbrett was intentionally removed from this Enigma and no longer is present.