Ive got a 53 plated ford KA with a dogey rear wiper blade. The last couple of years it has worked when its wants to, however yesterday when you try to use the wiper the blade spins all the way round and drops down to clean the boot paintwork.... quite handy when it comes to keeping the paintwork clean- but kind of useless at everything else. Any idea what might be wrong? Could it just be that the motor has given up the ghost?