I've got exactly the same problem. I don't think its a faulty motor though cos the max energy is for accelerating a full drum of washing from rest and I've tried an empty drum and still no luck. I did get some improvement from emptying the pump filter chamber but just like you, I think its a dodgy vibration trip switch. My next experiment is to bipass the sensor (when I find it).
Peter, Northumberland, May 2010