Mike have you tried looking underneath the dash with a flashlight to see what is happening while the crank handle is turned?
More feedback is needed.

The regulator is GM 598876. Appears to be held by two fasteners on the backside of the dash.
I believe the stainless piece is called the tongue. This part can be purchased new (reproduction).
There is a stop rivet at the end to prevent the tongue from becoming free. Maybe remove rivet?
https://www.classychevusa.com/index...13/category_id=339/mode=prod/prd1813.htm
Turning the crank handle in both directions and feeling a stopping resistance means the windshield is stuck (to me).
Be careful with exerting pressure on the windshield frame. It can warp and cause fitting/sealing problems later.
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Last edited by buoymaker; 10/28/2022 6:23 PM.
"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."