I would NOT spray out bearings with ANY kind of motor spray.....all that does is eat up the factory GREASE and flushes it out....then replacing it with bearing OIL is NOT good because oils are too thin, heat up then get even thinner, thus giving you a hot, now dry bearing again.
Ask any pro the same question and he'll give you the same answer....just replace the bearings if they're crunchy or not smooth. If you don't, this will just allow the bearings to vibrate, then allowing the rotor to vibrate and basically ruin the motor's performance, and possibly even lock the motor up, which now can roast the speedo.
So, after so much running, like when the bearings are worn and "crunchy", spray the rotor off and the can out (before you put new bearings in and while the old bearings are out).....and when the can and rotor is completely dry, then you can put brand new bearings back in the can, and reassemble and your motor will pretty much be like new again, other than the magnets being a bit worn, it will be new.
In summary, cleaning bearings is just a waste of time because even if you spent two hours cleaning them out, and re-oiling them, they will STILL be crunchy regardless.....you notice it's the same thing with a crunchy diff.....
when a diff is worn and is crunched, is very gritty and nowhere near smooth, do you take it apart, clean it then relube it and simply put it back together expecting it to be smooth again??? No....this is because the rings are grooved from the diff balls being scuffed and ate up from usage and dirt getting in....they canNOT be made smooth again....so what do you do? You replace the old diff balls and diff rings (and a lot of times it's the thrust bearing too) then reassemble with the new parts in order to get a smooth diff again.
The same goes for ball bearings....you can't just clean them expecting them to be smooth again.
Just replacing a couple bearings is absolutely nothing compared to buying lathes, brushes, springs, and tuning motors all day long.....we can finally forget all that stuff!!!!