Anyone seen anything this bad before? It's surprising that it continued to work as long as it did, without the slightest abnormal sound. Yes, that bearing is indeed worn to an oval shape. I can poke a paperclip between the shaft and the bearing!!!
This is at a place I'm renting. A call to the landlord has already been made. For now, I've made it quiet again by cleaning out all the metal shavings, rotating the bearing 180 (so the forces on the bearing are on the less-worn portion) and oiling the hell out of it.
Furnace manufacture date is 1976. Wonder if he's going to replace it, or spend the money to repair the blower assembly, which will need a new shaft and two new bearings.
By the looks of things, my assumption is that these are the original "permanently lubricated" (sealed, there is no oil hole) bearings.
Tip: don't wait until you hear noises before you decide it's time to apply some oil, as it's probably already too late. Of course, this applies only if your furnace has oil holes on the bearings. However, even sealed bearings may be re-lubricated by carefully drilling a small hole in the side of the bearing housing.
Anyways, this post is mostly just for your enjoyment and information. I'm not seeking help or advice.