Hi.
On this thread by
steve rolfeca:
Can i tighten sloppy Elephant Ear tuners?
You can find a great pictorial that doesn't necessarily adress your exact problem, but explains how to dismantle and put back together an open gear tuner.
A closed one is exactly the same (usually without the spring though, only the dimensions are smaller and the gears are not as easily accessible.
Edit: OK, it's a closed one then. If You take the string off and push/pull the shaft up and down, is there movement?
Regards
Sam