Bob, I am sorry I was not clear. What I am saying is that I had a slide balanced and in the enlarger. I switched to a different paper, which happened to be cut from a larger sheet and I used the new filter settings specified on the box.
For the initial paper, in 8x10, which specified that I use C10 M0 Y10 I found that I needed C15 M0 Y15 to match the slide.
I switched to the same Glossy RC paper but in 16x20. To balance this I cut one sheet up as I described above. The filtration on this paper was specified to be C0 M15 Y30. I then calculated that I needed C0 M10 Y30 for this new paper. I tried one of my freshly cut papers at this new filteration, having adjusted the aperture with a light meter. This print was almost exact match. What I was trying to say above is that the only prints that match were the ones cut from this original sheet. The subsequent sheets all had a magenta cast, which I attributed to various other problems, and always tested back with this initial cut sheet in 4x5 and 8x10 size.
So, what it looks like to me is that only the first sheet matched the filtration settings on the box. So far the rest of the pack needs about -10M from the looks of it.