Today I rebuilt the Thetford Aria Deluxe toilet in our 2004 MADP. The old controller started giving out (needed to hold down the flush button or it would close before finishing the flush process and I had to still add more water). It is original to the coach so I got a new flush mechanism/motor, controller, new seals, and a new toilet seat from Home Depot, about $320, total. MUCH cheaper than a replacement!
I pulled the toilet and installed the new parts this morning. It worked great but the trapdoor slide seal leaked because I over-torqued the mounting plate, so it wasn't flat and the bowl wouldn't hold water.
After lunch, I pulled out the toilet again and reinstalled the plate and it works Iike new again. It is even easier the second time. DW is now happy.
If you are going to own a rig like this, being handy is the only way to go unless you want to overpay someone else to do a simple job like this. I am retired so my labor is dirt cheap and I am "frugal". My cigar and sundowner afterwards were well deserved. Life is good.