When we first bought our Jayco (new)it stopped up on two occasions. Had to use a Flushmaster to free the clog of tissue. Learned to flush twice and had no more problems.
About ten year later I had a leak on top of the tank so had to remove it for repair.
Found a #3 Craftsmen screw driver lodged at the 45 degree bend in the toilet drain.
A friend had the valve jam open after about 5 years on a camper he bought new. He found a plastic drink bottle in it.
Like my screw driver, it was a gift from the guys who built it or someone who looked at it at the dealer before we bought them.