Originally Posted by Matt93SE

it's a common problem on 3rd gens..
what happens is the tiny gears on the odometer get gunked up.. tiny dirt particles get stuck in the white grease on the gears.. you basically have to take the thing apart and clean the gears off really well with a solvent that won't hurt the plastic but will get rid of the dirt and grease...

Fantastik, 409, simple green, something to that effect.. spray some on it, then use a Q tip and toothpicks to wipe things clean... put the covers back on and see how it works.
don't put any grease back on it, as it attracts dirt and will cause the probelm again later.. just leave it clean and dry.