[sourdough]

Is it a Thetford? If so, it may be leaking at the ball valve/seal in the toilet. If you have a strong urine smell it is probably a Thetford. Mine was designed with large pockets at each corner that held the water from the bowl as it leaked. It eventually smelled to high heaven before I figured out what was going on.

If it's the Thetford I would replace it with a Dometic. If not, or if it is, look for a leak around the valve/the seal in the bowl. The Thetford has two screws/bolts at the very back of the bowl (hard to see) that can come loose and let the seal leak.