Hi Beaka, I owned and ran an ST2 Startomatic for many years. I am guessing that your fuel shut off solenoid is the same as on my SOM. The governor, governor spring, injector pump rack and linkages are all internal and get lubricated with sump oil so they wear very slowly.
The fuel control solenoid and it`s linkages are all external so they wear much faster because very few people bother to lubricate them. These can easily be adjusted to shorten or lengthen the linkage as required. Another issue with these old solenoids is that they get filled with dust,rust and other detritus that prevents them from achieving their full travel. Adjusting the external linkages is nothing to be afraid of. A couple of pics attached.
Bob