Baxi Solo 3 PFL 80 not firing up?

Have been having problems recently with the boiler fan workng intermittently, it would struggle to turn and now it doesn't work at all. Pipes to and from the pressure switch seem OK, had managed to get the boiler working if removed and re-fitted, but not any more. The boiler light comes on but no others. The alignment of the fan outlet with the flu pipe is not good either and the gasket between them is worn (crumbling). Also just before it stopped working altogether the radiators would only get warm, not hot. Any ideas as to what the problem might be?