I've got a 2002 Chevy Aveo that runs and drives but there's a problem with the transmission. It will go into gear with a lot of play and make noises. It will try and come out of gear when you let the clutch out but if you hold onto the stick into the same position it won't move. In first gear the cars stick will try and pull forward and in reverse it tries to pull backward. If I don't hold onto it (very firmly) it'll make an audible pop and come out of gear.
I think it might be the shift linkage? I'm an old truck mechanic... I have no idea what I'm doing.