Edit: you edited before me!! But I don't adress it yet, since you explain the context more professionally. Thank you in this regards.
The machine is more then 40 years old. I attached the photo. The right handle adjust the zick-zack-width (I had to adjust the chassis to get it zero'd) and the left handle puts the needle 'left'/'middle'/'right' in the feet.
I had to cut some chassis on the right handle to the left and adjust the internal screws so that the axle of stitch width is exactly above the front-needle of the geering. It wasn't exact with a straight stitch prior to this.
I may add again: Me or my friends are capable of changing any axle or gearing to nm but I do not know what to request in the first hand. Engineering is very, VERY, hard.... :(
Yea
I would die for 10 mm. I would be in to adjust the machine while sewing for any step lenght larger then 5 but 10 mm would be perfect.
I can change gearings, leverages and axles if I understand what to communicate. I am not bound to the current chassis and motor. I can construct a chassis afterwards rezpecting current alignments within nm.
I circled the change in blue. Leveraging the handle could be the case but axles wind on their own. It is a mind fuc* which can only be put in perspective by Engineers, imo.