Hotpoint Dishwasher LFT114UK with faulty pumping.

Just collected a customers Hotpoint LFT114UK dishwasher that was made in April last year with a very noisy rumbling from the recirculation pump and no water flow through the spray arms?
Have stripped down the circulation pump which is combined with the heating element and found that the impeller has had some damage to the vanes and the end plastic outer ring was off that covers the vanes. Most of the permanent magnet rotors I have come across in drain pumps are fixed directly to the shaft with no free rotation.
This circulation pump which is the permanent magnet rotor type fits into the impellor and can rotate about 380 degrees before it actually turns the plastic impeller round. Is this why the pump is rumbling away when in the dishwasher. If mains are put directly to the coils of the motor it does rotate on the bench. The shaft has two flats ground on either side of the spindle
Anybody know if this newish pump is a feature with this 380 degree movement before taking up the slack and turning the impeller?

Had carefully re-installed the plastic ring over the impeller thinking this was the problem as it was floating around in the housing but exactly the same noise in generated when put back in to the dishwasher. Did not want to order £91.00 worth of pump if I am looking at a red herring.

FlyingBrick