I have a 84' Firebird remarkable with functioning pop ups. The drivers side always works fine though the passenger side will get stuck up. If I give whatever mechanism the black spinning cap Is, a very light tap, it goes down. Also works fine if I flip the switch on and off fast, making them go down before getting all the way up. Any google search I try to make only gives results for completely dysfunctional motors. I have greased everything that looks greasable, and checked connectors. Just a worn motor?

 

Might have a broken tooth on the plastic gear inside. Buy a rebuild kit. It's not much. I'm rebuilding one of mine this weekend.