It's more likely to be a problem with the relationship between the negative and the lens board. These must be parallel.
There is a step by step procedure for this, perhaps posted in APUG, but I'm unable to put my finger on it just now. I'm at the stage of having done a few prints with new darkroom and then got a second enlarger for parts, merged the best into one enlarger (B23CII) and now I'm ready to tune everything from soup to nuts, may drive me nuts,
from exposure through development through enlarger alignment through print development. One film, one developer, one paper (till mastered).
Something about making a scratch ruled negative, and something (separate) about using two mirrors with a hole scratched out in the mirror in the negative stage. Maybe one after the other or one instead of the other.
A step by step guide or link to such would be greatly appreciated by me and the OP I'm sure. Thanks!