I'm rebuilding a Myford ML4 (3.75" centre height) lathe at present. When I bought the lathe I found, too late, that the headstock spindle and bearings were badly scored. I bought another headstock, in good condition, with the intention of using the bearings and spindle to repair my ML4, but after getting it home, found that it was an older type with a smaller bore and chuck fitting. I bit the bullet and had the damaged spindle hard chromed and reground. Yesterday, I drove the bearings out of the spare headstock and fitted them to the lathe; when I went to fit the spindle, it was very tight, and when fully home, was almost impossible to turn. I dismantled everything and measured to OD of the bearings; the original bearings were found to be .003 smaller than the ones I used as replacements; measuring the bore in the headstocks showed the same difference with the spare headstock having the larger bore. My question is, what would be the best way to adjust the bearings to size, do they need to be line-bored after fitting to the headstock? If you're not familiar with this lathe, the bearings are plain bronze split bearings mounted in a split headstock bearing housing (not removable bearing caps). Martin.