I'm using an LPL 7700 Pro colour head, and dialing in the multigrade settings. When I went from grade 3 to 3.5 today I had to add about a half stop to the exposure time. Is that usual? Ilford's info states that using the yellow and magenta channels should reduce this problem. They also state exposure times should remain constant till grade 4. I am wondering whether the developer had started to expire or something, but I don't think it was that.
I was using MG IV RC paper and Ilford MG developer.