Hi, I have a hoover ultracare 1500 and it won't spin?

My hoover ultracare 1500 isn't spinning at the moment. It will go through the wash cycle but then just carries on draining and the spin doesn't kick in. The other day i took the back of and undid two bolts that hold the motor, took the motor off, looked at it and then reattached it. it then worked for one cycle. but has stopped again. We would welcome any suggestions. We now have a humungous pile of washing. 11/3/09