Rodney sells rebuild kits and i believe also has aluminum gears. Rebuild what you have. Not sure what year but you might want to upgrade to the 87 88 headlight motors. Do a search and you'll find several threads on the swap. Need both motors and complete wireing harness. Not really hard to do and better motors. Not sure why 1 side is worse than the other.
Oh and edit to say welcome to the forum. You'll find lots of helpful people and info here.
[This message has been edited by DLCLK87GT (edited 12-10-2009).]