Mini lathe spindle register wear

The register on my minilathe seems to be wearing - chucks which were once interference tight are now a few 1/100ths loose. I'm not entirely
sure that it's the register, but I suspect it is.
The register is about 3 mm high and measures 54.93 mm diameter using a digital verynear, but I'm not sure how much I trust that.
I was thinking of two plans to deal with this, and would welcome comments.
Plan A, get a 55mm x 13mm outside diameter bearing, cut the outer race in half lengthwise as 13mm would be too long, and fit it in a slot cut in the spindle. Questions here include: How accurate is the outside of a bearing?, How do I cut it? and Would it be too hard and wear the chucks?
Plan B is to fit a cast iron ring to the spindle and then machine it to size in place.
Plan C is to buy yet another new spindle, but that's about 50 with postage etc.
Any comments?
-- Peter Fairbrother
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