Can I Repair 1971 Chevy PU Drivers Window Regulator?

[gwignall]

I removed the wing window and glass to replace the felt channels on the 1971 Chevy 1/2 ton my husband is restoring. I installed new felts and re-installed the glass. All went well....window rolled up and down just fine. Put door panel back on....window wouldn't budge. Took door panel off...window regulator is still stuck! I can see the "gears" trying to move when I turn the handle clockwise, but at the risk of breaking glass, I didn't force it. Are there adjustments I can make to the regulator (in the door or if I take it out of the door)? Thanks, Gayle