sounds to me like a Thetford a bad design needing a active hand stand. Prise it out as My lord says.
www.thetford-europe.com click service cassette toilets follow through to the repairs and download the pdf it covers ALL models just search for yours.
It may not be the fuse easy test is turn on the 12volt system and a light in the toilet cubicle and press the flush button if the light dims then its not the fuse but the pump is either knackered or jammed. C2 model the pump access is through the toilet roll holder this is a push in fit so gently prise it up around the rim pull it out and you will see the flush pipe and pump which will be held down by a plastic cage One cross head brass screw hold the cage unscrew that and lift both cage and put out. Turn the pump upside down and with a thin screwdriver gently turn the impeller for around 10 revolutions now to test. either replace (no need to fix) the pump back in water in the tank or saucepan if no water in tank (pump must be submerged never test a pump out of water ) press flush, fine if it works knackered if it doesn't and you HAVE established current to the pump by above test or using a volt meter..
Buy a new pump as a spare if it does work.
If still no current at the pump it may be the micro switch. Look in the pdf for removal of micro switch.
bob uk
September 2014
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