Adler should have a mechanics manual for that machine. See if you can get one. The movable knife in the Adler 291/295 series is the one they copied when they designed the current M series that is the 867, 868, 869 machines. It is different than the one in the 467/767 machines. I could help you there. You should have parts list, operations manual and mechanics manual for that machine. it tells yo how to adjust and replace the trimming knife.
glenn