I broke off the metal tabs that hold the lid to the can; damaged the commutator, lower bearing housing (made of brass). It's actually kind of hard to ruin it, but I manage the best I can.

Yea, if You do want to pack the bearings, You have to dis-assemble it. If You grease without taking apart, You are doing absolutely no good and are only greasing the shaft (unless You oil and it accidentally gets into the race, but oil in the high speed motors gets slung everywhere and is no good).To pack bearings; do this:

unsolder motor leads marking which side is negative and also marking that particular brush (if used) so as to get it back on the right side.

Unsolder capacitor leads.

Remove brushes.

Pull pinion from motor shaft.

using small flat blade screwdriver or needlenose; GENTLY pry up the metal lip holding plastic lid in place. Don't overkill, lift enough for top to clear.

Pull plastic top off of can; the rotor assy. may come with it as sometimes the upper shaft is tightly held into the upper bearing.

Holding onto the rotor magnets (the strongest part of the mech.) pull the shaft out of the top lid; the bearing may come with it and this is alright; You can pack it with it stuck to the shaft.

Take a large punch the right diameter for the lower bearing and GENTLY tap it out of the lower can assy. It is a steel sealed bearing housed in a brass collar. It's easy to kinda squish the bottom part of the brass, but as long as it isn't totally collapsed into the bearing itself; it'll be alright. Pack both bearings with heavy grease, wiping off the excess. I use a plastic hyperdermic c.a. applicator with plunger; center it on the race, and push it until I see it 'geyser' out of the entire race.

After cleaning the lid and lower can of brush dust, etc. use a non magnetic (c.f. rod, etc.) to put through the lower bearing and running it through the lower can opening. The bearing will be suspended in mid air by the permanent magnets. With Your other hand; use something to push it down and get it started to friction fit back where it belongs, so when You remove the guide rod; it won't jump and stick to one of the magnets.

Use a same diameter punch(or close), put the can on the table and press with hand pressure only to push the lower bearing assy. back into place; don't overdo it and crush the lower side of the bearing brass housing.

Clean the commutator any way You see fit (it is paper thin, so don't scrub with sandpaper) I clean with alcohol and cotton swab

Put some green locktite (the kind that is safe for plastics) and lather the tiniest amount into the SIDES of the bearing opening in the top of the lid and press the plastic cap back on. DO NOT PUSH THE CAN TABS YET!

Set the assy upside down and tap the pinion back on; use something plastic like a heavy screwdriver handle to tap it flush; then use needlenose pliars with one hand opened enough to allow shaft through pliars and tap pliars until pinion is where You think it should be.

Now, push the metal can tabs down using a punch and hand pressure to start it, then needlenose pliars and hook lower jaw of pliars to divot in can and with the upper jaws on the tab, squeeze jaws together to finish the bend.

Re-install brushes and re-solder.

You should never have to lube again, ever. You will be happy to know that the excess grease will wick upwards out of the top and bottom of the can and will not goop up the insides or commutator. Only the excess will do that until the bearings reach their pressure equilibrium with the grease. The rest of the grease will stay inside forever. Not much will wick out, and I wouldn't try to pry in there and remove it as it will form a dirty crust that actually will shield the bearings from dirt entering the balls.

I use the Red colored grease from Phillips that is used in 'The Greaser' and is used for hi temp, hi torque, hi speed applications;
It is recommended by alot of top heli flyers. Tri-Flo grease stays put rather well, but not quite as good as this red stuff, IMO

TIP: The metal tabs don't like being bent, and before You put the guts back in the empty can, You can paste flux and solder a little build up of solder at the bend point. Just a little shiny amount. If it's too hard to bend after that; just scrape some off with exacto knife.