The target was printed on the same 36" role photo rag paper. I bought 20 roles to get through a print job.
The scuffs typically are in about the same position, but I think the print head scuffing the paper is causing build up on the head which in turn causes more marks elsewhere.
The humidity in my studio is consistent and low.
My test prints are smaller (about 10" high of the role) and periodically get the same marks, though it doesn't seem quiet as often.
I have set the platen gap to wide, but every time I turn off the printer it resets, which makes me wonder if the platen gap is changing. (I see no difference in print quality looking with a 6x loupe.) I will try entering a wider platen gap using a custom paper and see if it stays when the printer is turned off.
From advice in the service manual, I also checked all the paper suction air holes and foam filters. Some of the holes had a lot of paper dust in them and one foam filter was missing. I cleaned out the wholes and replaced the one foam filter.
I will do some more test print today. It makes for very tense printing not knowing whether marks are going to show up in the last 12 inches of a 30x50 print!
Will you be able to get the custom curve done today?