I just finished installing the new bands in the transmission,and I don't remember which way the small pin goes in the slow speed adjuster shaft. Does the long end go into the spring and band ear, or does the short end go in?
Could you post a picture? I have been going over your question for a few minutes, and I don't understand what small pin you are talking about.
If memory serves, the long end goes in the adjuster and the short end goes into the band ear. Check to see you have enough length on the short end to secure the spring. Don't rely on a 69 year old memory (mine) ;^)
The #3419 Low Adj Screw is hollow to accept the low pedal shaft. This is the one used for the non-demountable ear bands.
If you installed demountable ear bands, the #3419B is used, it is one piece with short stub end to fit to the band ear.
Now sometimes folks use the earlier #3419 and stick a stub shaft in, but caution, loose pieces can come out. Best to modify an earlier Low Adj screw with tapped hollow hole, and turn in a cut off bolt, secure it with Locktite too!