thanks

The rear bearings are a sealed unit, replacement is the only option.

After all these years I think they have well and truly done their duty:dead:

Actually only one of the two is sealed, and only on the outer facing side so you could re-pack it, however they must be pressed off and then back on so most folks recommend replacing them. Mine looked new and came off so easy I could probably re-use them if I wanted. In your case, if they are already howling, it's time to replace them anyway.