Thank you for the question - all the ball bearings were found rattling around in the bottom of the sebo body, not the motor casing.
However since posting my enquiry the sebo started smoking, and upon dismantling, the motor was the root cause.
Purchased a new motor from Approved sebo dealer, fitted it this morning and vacuum back to working order.
Took the opportunity to examine the old motor and the one of the bearings had completed shredded itself to pieces.
Thank you again for coming back to me, however problem now resolved.