having problems with the above,when pumping the flush handle i get very little resistance from it ,as if the O ring or washer on the plunger is not at it's best giving me only small amounts of water and spurting as opposed to a constant flow .
I have noted small amounts of black rubber substance in the bowl after trying to flush which is leading me to the conclusion that it could be a washer thats disintegrating and causing the trouble.
Has anyone come accross this? have looked on Thetfords site and there is no mention of a repair kit i.e.washer set.Have seen a complete flush handle complete with resevoir for sale in a c/van shop for £40 which seems expensive when it's probably only a washer.Any advice appreciated.By the way yes there is water in the flush tank.
2 possibilities,a pipe has come off at the bottom.or just as expensive the base of the plunger has cracked and the whole plunger needs replacing.look for signs of water at the base of the toilet to give an indication of a cracked plunger.
This is a classic sign of the Pump Retainer having broken; see item 26A in the exploded drawing you can download from my link here.
Remove manual pump and examine this item first. It's relatively ease to locate and this piece tends to have three small clips that hold it in place, one of which has probably broken.
Replacement retainer is about £8-11, depending on where you get one. Most caravan accessory stores with a Thetford parts rack would have one.