I'm in no way an expert but I'm having similar probs with mine. It goes through the whole wash (with a little crackling noise whenever the drum's rotating that I've never heard before) and at the rinse stage it pumps and starts to spin but the drum won't even make it a quarter of a turn.
My research leads me to think it's either the carbon brushes going/gone (which might in turn have damaged the armature, depending on how long it's been going on for) and may mean a new motor) or it's the motor. Both are fairly easily available and, as long as the rest of the machine's OK, it's probably worth doing. Brushes should set you back about 25 quid and around 100 for the motor.
Gerard, April 2008