candy aq141-banging noise on spin?

Candy aq141,has been trouble free for over 5 years and now there is a massive banging noise coming from it when on full spin.Have checked all mountings etc.,and all are fine.Seems to be a lot of "front to back movement" on the drum.Should there be any horizontal bracing of an sort at the top of the machine?
Also,grooves on motor spindle and grooves on drum flywheel appear to be offset,although belt stays on!!

Any input would be much appreciated

Many thanks in advance,
Andy