During service and testing, a special crank was available. This useful crank could be easily fixed with an internel collet (3mm).
The tool number in 1.000.977

Her are some pictures of the crank. I use it frequently during the service procedure and for trouble-shooting.

Yes, I know the extensive collection of tools for the CURTA from your predecessor Hans-Rudolf Roshard (formerly Curta Service Switzerland).
Here is a picture I took during a visit to his workshop:



The whole collection can be admired here: Curta Tools From the Collection of Hans-Rudolf Roshard

Thanks, things look familiar to me. But there are always new tools.