Could you get a local engineering company to grind the shaft down and fit a hardened steel sleeve the same outside diameter as the original?
A.
Adrian, for sure that would be an option, and supposedly cheaper than replacing the TS shaft by a new one (107£ excl VAT for the replacement part)? Anyway, in both cases the cranckshaft must be dismantled and reassembled, I suppose? Only problem, I think, is the maximum thickness of a sleeve (inner dia cannot be less than 22,2 mm which is the inner dia of the bronze bush, outer dia 25,4 mm...). Could it be an option to grind the shaft to 7/8, and to use a ball bearing (outer dia 1"7/8 = outer dia of the hardened ring, inner dia 7/8)? I don't find a suitable roller bearing...
Ludo