Looking for replacement shower wheel from 70s/80s?

I have a shower from the 70s or 80s and i would love to replace one of the wheels for it, instead of replacing the screen.
I cannot seem to find them, as they are no longer made, but surely there must be somewhere that has old stock or dismantled screens that we can get them from?
Any information would be greatly appreciated. The metal part has MELBOURNE written on it, and the wheel was from Anthony Bearings Australia

Rachel R
November 2011