Sunroof won't quite close

On a 96 GrandAm GT the sunroof works fine except it doesn't quite completely
close.

I took the glass out and checked carefully for any track problems and don't
see any. Cleaned it up real good too.

It's pretty clear that the slider needs to go forward about another 1/4-1/2"
for the window to completely close. Problem appears worse on passenger
side.

Have read one post here that a pin in the motor that positions the gear had
fallen out and the gear was off a tooth. Sounded interesting. As a matter
of fact, my sunroof may be trying to go back a little too far. Another post
said check for debris in track.

I may go ahead and expose the motor, but looks like a bit of a pain. Any
other ideas or checks.

Thanks,
Dave