I have found some time to start digging into my new Klein-Adler 2. The mechanics look good. The carriage moves smoothly. The rollers work well. Some of the slugs stick. This is a front-action (the right term?) machine, which means that the slugs make contact with the platen through a forward motion rather than by swinging upwards. The typing motion has three joints to it.
It appears that two forms of momentum pull the slug back, one created by a spring and the other, I think, created by the silver plate underneath. The slug ascends the plate; so, upon releasing finger-pressure on the key, the slug slides back.
The question is what is preventing some of the slugs from moving smoothly. Does it simply need some more cleaning? Are the slugs partly bent?
I have to be careful. If the metal has to be massaged into the right position, I need to do it correctly. Otherwise I could make matters worse. Someone has worked on this before, as indicated from some scratched screws underneath the machine.