David, I might have the same problem as you. I too have a minor mill/drill of some 20 summers, and there appears to be a slight 'ovality'? when milling. The clamps for the head, originally nuts, I have converted to a handle type arrangement ( there was an article in ME some years ago along with a few other mods). I still have the manual!! Along with the exploded parts drawing, but cannot fathom out how to get at the bearings to replace. I am seriously thinking of selling it cheapish to someone with the time to fettle it up and getting a WM 16 with digital read out. It will be a great help to get the head up and down without the spindle position going walkabout, as well as accurately lowering the head to get that final thou off. Looks like we are in the wilderness with these machines and they could well be the last two left, in which case we wil have to breed them for future spares!!