Rick your regulator gear has a fair amount of wear as seen by the cupped gear ridges. The crank handle shaft may be as badly worn, or perhaps not. You won't know until you remove it and get a closer look.
The good news is there is a Legacy Tech Tip
Windshield Crank Rebuild which should give you a good starting point on figuring out if you can fix your own.
If you find out self repair is beyond your capability,
Chev's of the 40's offers a rebuild service for your unit.
