Brushroll motor
Thanks for the speedy reply, Parwaz... 
I'm mystified as to why the (permanent magnet) motor tests 'open circuit' at any and all positions of the commutator against the brushes. If there is no thermal fuse, this would indicate that ALL of the windings must have failed!!
Yes, I'm checking just the motor (branded 'Johnson'), the PCB is ok.... 
I'll have to report back the price of a new motor, and see whether he is willing to spend the money... 
All best
Dave T