Another thing to check is the transmission frame, if the original
pot metal frame is still in place.  Even if it was still good a few
years ago, it might have finally started to warp.  When the shape
begins to change, the wind motor and roll will run slowly for awhile
before it finally won't turn at all.

To test it, remove the roll and the drive chain from the wind motor
shaft to the input shaft, and try to spin the transmission input shaft
by hand.  If there is any drag, the transmission frame might be warped.

Art Reblitz
Colorado Springs, Colorado
http://www.reblitzrestorations.com/