My coins are clean. I've rarely used them since I got a bag of brand new ones. As for the mechanism... it's pretty clean as far as I can tell. I've carefully wiped down both sides of the track. Is there any kind of lubrication (dry or wet) that needs to be used with these. It looks to be a fairly maintenance free mechanism as long as it's kept clean.

On a side note... anyone know what the green lit button is on the front of the circuit board mounted to the front of the coin mechanism? I've never been able to figure it out.