Any way to open the smoke unit to access the piston? Noticed one of the tanks wasn't producing smoke, opened it up and the smoke generator wasn't doing anything. Looks like the black rubber peice on the piston is twisted a bit, possibly binding it. Doesn't make any noise or anything. Switch it on, everything hooked up. Took the 2 screws out on either side of the piston, but the cover didn't want to come off. Hoping the piston didn't bind and jack the motor up on it.