Hoover washing machine goes through washing cycle but wont spin?

Hoover Quattro front loading washing machine
The washing machine motor carries out the normal drum washing action but fails to spin at any time during cycles .The door opener also stuck fast.I managed to free the door mechanism after removing top cover. I examined the remainder of the motor and wires for obvious problems and nothing seemed untoward. on trying the machine again the spin worked correctly and everything back to normal.Everything went well for about four washes but then the spin failed to work yett again. This time the door opener opened correctly.
Could it be the door mechanism is causing the problem or is it coincidental.Next to the door switch mechanism there is a clear pipe which runs to the rear of the drum .Could this have any bearing on the problem !!. Greatful for any ideas