Nothing to add about taking it apart! Just adding information on how I repaired Calistas bearing.
I bored out the outer tube, and cleaned the shaft up in the lathe. I then made up a phospor bronze bush to press into the tube in the lathe, and finished off the inner diameter of the bush to be a good sliding fit with the shaft. I drilled through the grease hole and made a slot along the bush to distribute the grease along the shaft.
Not that I think you all have lathes in your garrages, but it can be repeated by taking it to an engineering workshop.