inspect the window guides. Maybe the lithium grease dried out and then need to be cleaned and re-lubed but short of removing the motors and testing them I don't know of a way to determine if they are done.
You don't have to remove the glass and you can use spray lube to see if it's a lubrication issue. If it is a lubrication issue, you will most likely want to remove the window system for repair and reconditioning.
Part of your reconditioning would be to disassemble the motor and check the commutator and brushes. If they are bad or worn, there are many dealers that sell replacement GM motors or will recondition your originals.
Either way, get an electric window maintenance manual and study it before tackling the problem.
A forum community dedicated to 1st generation Chevy Camaros owners and enthusiasts. Come join the discussion about performance, builds, restoration, modifications, classifieds, troubleshooting, reviews, and more!