Thanks, sounds like a good fix in the cases where the plastic collar breaks.
Not a problem I have ever seen, though.
The faulty ones, I have dealt with all had the commutator deformed by over current
after brush fails and I found no solution to this other than locating a replacement motor.
It's usually diagnosed by a frozen motor, alternatively a motor that will rotate unevenly by hand
and often only in one direction, blocking the other way.
Martin