Are you sure it's not just a case of light leaks or surge marks on the negative? Those would produce light areas in the print, which would be fixed in orientation (given a negative inserted the same way each time) and would scale with the enlargement factor.
To eliminate this possibility, try rotating and/or flipping the negative in the carrier and see if the "glare" marks change orientation with the negative (or simply inspect the negative for a dark region that corresponds to the light "glare" mark you're seeing in your prints). If the glare moves with the negative, it's on the film; if not, it's something in the enlarger.
I have a 120 camera that has a light leak, but it's not in the bellows or image mask area, it's in the film supply or take-up chamber; I know this because I see a shadow of a pin roller in some/most of the light marks. However, the fogging shows in an image, because it's on an area of the film that will be in the next image, or was in the previous image, and in a B&W print or scan it looks very much like "glare"...