Igor, Igora, igoretta its this big family. They might even live near you.
I don't know why that family gets around so much but they do, then they sneak in people's houses and tighten up the 500s and 503s wheels every chance they get. They seem to be able to home in on those machines in a freakish sort of way. It may be a conspiracy.
Just for fun, have you used brake cleaner to vaporize a foam cup?