It may be possible that the balls ran over the hair and got slightly out of alignment. Try playing it some and you might be able to wear down a new track, if not you may have to take the bearing apart and try to get it lined back up
It’s quite possible that the bearing is beyond repair. I also like to work on bearings but after three or four unsuccessful cleaning attempts i usually give up.
Not sure if it’s been mentioned yet, but axles can shave off bits of aluminum (presuming aluminum threads in the halves) if not threaded properly. These shavings can get into your bearings when you unscrew the halves. Acetone will NOT dissolve these, so they need to be vigorously cleaned out and then blown. As with any other grit.
I see, I don’t have acetone and I think it’s a bit more dangerous than paint thinners. So Gum Spirits of Turpentine is going to have to do it :). You say clean it vigorous, what can I put it in so I can shake it without it spilling? For past cleanings I have used a small glass jar/cup.
I don’t know about Turpentine. Mineral Spirits are fine in most plastic containers, and acetone which normally dissolves plastic is fine in “Type 5” plastic (I don’t know if that’s the correct term, but on the recycling symbol is the number 5). So I use a contact lens case. Requires less fluid and lets you shake vigorously!
I would suggest that a good high pressure canned air will do the job of removing most particulate that acetone can’t remove. Turps will be fine just the same as acetone in terms of use in glass, but won’t be as good at removing organics particulate like oil. If you want to clean the bearing efficiently then a good sonicator can’t be beaten (I believe typically described on threads here as a jewelry cleaner) - its a shallow water bath that you place your item in (inside a glass container with your solvent in it). The sonicator then ‘vibrates’ your bearing clean, for want of a better simple explanation. This is really quite a good method, and means you can leave it to clean for a while without having to stand there shaking some pot. One other thing I’ll mention here is that if you are going to put solvent in a pot with a lid to clean a bearing, you MUST make sure you take the lid off regularly and make sure the sealed container doesn’t experience changes in temperature. Please be careful! Some places sell darkened glass containers with vented lids that are still sealed to liquids. These are ideal.
Not mentioned yet: as a last attempt for bearings that I think might be “done for”, I usually try the metal polish technique. I’ve recovered 2 bearings from the brink of death with this!