A new one should not be too hard to make on a lathe.

Another possibility is to sash the thing into a thinner form thus making the hole smaller, however it has to be held tightly around the outside or that will expand as well.

Only other thing is to knurl it internally. They used to do that to the valve seals when they rebuilt the old car engines. It doesn't last as long but it is already what, 30+ years old
? If it lasts a third of that something else should be wrong with it by then.

You could try turning it 180, top to bottom and let whatever force work on the less worn parts. They are almost never worn equally. It also might be exchangeable wit the back bearing but that would be my last resort.

Have any machine shops in your area ? One of them might be willing but the cost might be a bit high. Also, a jeweler might have a lathe capable of doing it.