I had a couple of bearings blow up in a sound head once, due to a bad film jam. It was the lateral guide roller in a Century. The things felt like they were full of gravel! Of course it was on a Friday. (These things always happen on Friday, don't they?)

Obvuoisly, they were trashed and the projector was down until those bearings were replaced. I had to think of something and fast!

I had nothing to lose and everyting to gain so I took them out and dropped them into a Dixie® cup full of Xe-Kote™ and swished them around for a minute. Big gobs of black junk and little bits of things that USED to be bearing came gushing out.
I took them out and spun them a bit to work them and loosen them up and then gave them another bath.

After I let them dry they were good enough to get by with until the replacemants arrived.