Ok Sweep is up and running again The cheapo £3 motor turned up from fleabay and has been fitted.
This is the old knackered motor at the top and the new one at the bottom:
First job, having noted which of the motor terminals is positive (red dot) remove the filter board from the end of the motor:
Solder the filter board back on the motor and checked the rotation of the motor by plugging it in the board and running Sweep up.
Then the tricky bit removing the gear. I tried a puller but to no avail and ended up cutting the shaft of the motor off and using my lathe to drill out the gear. (The attempt with the puller damaged the gear slightly )
The gear has been attached using Loctite 438, so it needs some time to go off. So final pic: New motor all fitted together:
To reward Sweep for all his hard work I gave his visor a polish so hopefully he will be able to see a bit better and finally relented and fitted his spare set of front brushes as they were getting a bit thin. Anker seem to sell these as spares but he has been used for 18 months so far on the first set, and so long as I steam them straight every month or so, they have been working well.