Black and Decker 7604 bearing info.
In case anybody else ends up fighting with one of these, I've recently stripped mine and repacked the bearings. Most of the online info I saw gives you proprietary B&D numbers, and I personally hate having something in a million pieces while I wait for parts, so maybe it'll help somebody to know what bearings it needs beforehand.
The ones in mine (assuming original) were both Japanese, labeled "Nachi NB". They are also both metal shielded on one side and rubber sealed on the other.
The larger one on the chuck end has 6001Z stamped in the metal, and 6001NSL in the rubber. The rubber sealed side was on the outside (nearest the chuck).
The smaller one near the brushes is 608Z in the metal shield and 608NSL in the rubber. The rubber seal is toward the inside on that one (nearest the armature).
Hope that's of use to someone. Be warned, this thing has a lot of old plastic in it. It's also got the brushes mounted inside those little Black and Decker plastic housings with the pointy Z-shaped contact pin. One of mine was already missing a chunk of plastic and the contact pin was half gone. I'll have to solder the new brushes to the contact plates, and probably reproduce the pin with solid copper wire. Hope it works. I bought that thing decades ago for dirt cheap and surprisingly grew fond of it for its compact size.