While you wait for answers, we may have found some information which could help you.
Click here for Bell Howell Projector ManualBell and Howell 626 projector - no volume?
How do you replace the belt on a Bell & Howell #1421 Super 8 Projector?
Eumig 610D?
Canon S400 projector - take up reel does not turn?
How To open a Reflecta Diamator AFM?
Bell & Howell projector?