If I remember rightly the FL884 does not have carbon brushes
It has a pully tensioning device on the end of the motor spindle
If it is not running correctly (erratic or not getting upto speed) it could be the capacitor has gone low value so not giving the ooomf to start the motor properly.
SWITCH OFF AND DISCONNECT FIRST
With the top removed you will see a bar across the centre from left to right, approximately in the middle underneath the bar should be a capacitor (around about 12 micro farad rating I think but dont quote me).
The capacitor has some terminals on one end and is bolted on by the other end.
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