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The most challenging part of this machine was the restoration of the case mounting system. The casing is held together by a clamping mechanism and is ultimately secured by four bolts on the bottom of the machine. When I received the machine, the casing was not properly closed, and further investigation revealed that several parts were missing. I had no clear understanding of the original design of the mechanism, but using the available parts I managed to reconstruct it to a level at which the casing can once again be securely closed (see pictures below).

In addition, the machine required the usual cleaning and lubrication. At the time of writing, the carry mechanism of the result register is still not functioning reliably. It sometimes works correctly, but at other times it does not.

In December 2025, I decided to open the carriage to investigate possible improvements to the carry mechanism. It turned out that, in the upward position, there was only marginal clearance for one of the many control plates in the carriage (see picture below). In the addition/subtraction position (down), the clearance is more than sufficient, but the rapid upward movement after a calculation may have been too fast for the carry to reach the extreme left position—especially when not all carry movements of the individual digit wheels run smoothly.

The problem was solved by removing a very small amount of material from the right-hand control plate.

  ....  Clamping system: reconstruction of missing parts ....

  To ease maintenance the carriage can be opened.  For a procedure see:

  Carry problem solved

Clamping of keyboard cover

Case removal procedure:

 Clamping of carriage  cover