I am doing a rebuild on my lathe and I am having some trouble with
oily spots of the casting. I have tried heating and cleaning
repeatedly, but it wicks oil and the paint won't adhere. Can anyone
suggest a way to deal with this? I seem to recall a sealer of some
sort that would serve this purpose well, but can't find it from
google.

Also, as a side note, I had my lead screw reground and had new half
nuts and a new worm gear made by REMPCO for less than $700. I was
very pleased with all of my dealings with them and the quality of
their work. I am also replacing my compound screw and half-nuts with
a precision ball screw. I got it with oversize balls to reduce the
backlash to ~.001 and as I will be using a DRO, the .003 per foot
accumulated error in the screw was not a big deal to me. Just passing
this along as food for thought for others.