I lived in our 5th wheel for 8 years and never rebuilt the toilet. I did take it apart and removed the rubber seal and cleaned it of the calcified water crystals. Then reinstalled the rubber seal, and no leaks. I had to do this about every 6 months or so and it took all of about 15 minutes. The toilet is in two pieces and it is held together with a large clamp, easy to seperate and see the rubber seal. Worst case the seal kit costs about $15 bucks but once apart you can see that they are easy to clean. I also would run a flat blade of the screw driver over the ball edge and also remove any rough spots.