Getting AF Alcos running again after layoff

Hi -

Once-running "original" engines that ran no longer do - it's the reverse unit.  PLEASE DON'T WRITE IN TELLING ME TO REPLACE THE REVERSE UNITS.

There's got to be some trick to get these things cycling again, they stop working after they sit too long.  Right now they just light up

but the reverse unit doesn't kick in.  Can anyone tell me from experience what to try and in what order?  I read about fingers, etc but

don't see them or how to remove/clean them (if that's a thing).  I see the drum that's supposed to rotate, but the latch that sticks through the outside doesn't

seem to move anywhere so I won't try and force things.  Also, the "lever" at the end - that's (I think) to lock it in one direction?  

Thanks for your help -

Tom