Thetford Cassette Toilet won't flush

Thetford has repair/parts instructions online and you can also find a lot of YouTube videos showing pump replacement. You access the pump from the top of the unit. For my model the access is under the toilet paper holder. I am not sure but for your model I believe you need to pull off the lever and remove the flush control tray. Drain the tank first.

The clicking sound indicates the pump impeller is stuck with sediment. You might be able to move the impeller gently with a screwdriver and revive it. If not the pumps are standard and readily available for about $50 from Amazon and elsewhere.

https://www.youtube.com/watch?v=nNxVUitXi7o

There knock off pumps made for other stuff that look exactly like the ford one on ebay and Amazon for like 20$ you just have to look. Also, check the line to see if its clogged with sediment, as stated above it may clog the pump or the line. Sometimes the line falls off the pump also.

Everyone was helpful! The you tube video answered a lot of questions and I was able to get the pump out and order a new one. What do you use to flush the dark slime down in my toilet's fresh water supply tank, other that the $31 a gallon stuff? Just fresh water, maybe with a few drops of bleach???

"Dark slime?" No idea what that is. Chemicals for the toilet? Just add some to the cassett tank with some water. Dont follow the directions and add to the water tank. And i wouldn't add bleach to eaither tank. If it has stuff in the tank, take off the site glass and flush it out. I hosed mine out from the pump compartment. But i also had a bellows flush. Im sure you can do the same.