I had the new pinch rollers and star wheel assembly installed on my Z3100 44" printer on Wednesday, 2-13-08.
Installation of the new star wheel assembly went very smoothly. The new assembly has two positions, actuated manually by pulling out or pushing in the black buttons located at each end of the assembly. Pushing them in lowers the assembly into the normal down position, and pulling them out raises the assembly, hopefully resulting in the elimination or reduction of star wheel marks on some problematic papers.
Installation of the new tan/brown pinch rollers was more tedious, but went well after the engineer clearly understood the use of the tool included with the installation instructions (which were included in the package containing the parts). It was not necessary to tear down the printer in any way, except to replace a couple of the pinch roller holders that broke during installation.
Since the installation I have experimented with several of the papers that I previously had problems with: Harman Glossy FB AI, Ilford Galerie Gold Silk, Epson Exhibition Fiber, and HP Premium Plus High Gloss Photo Paper.
Of the above papers, the only one to show pinch roll marks is the HP High Gloss Paper, and this is only evident when calibrating or profiling the paper. This is of no importance to me, as I do not use the paper very often.
So far, star wheel marks have been very light to non-existant on the above papers when printing in color. However, they are visible on the Ilford Galerie Gold Silk and Epson Exhibition Fiber papers when printing black and white, primarily in the deep blacks. Of these two, the star wheel marks are most noticeable on the Epson paper.
I am printing on all of these papers with the star wheel assemble in the up position. All papers tested have been cut sheets, and I only had a sample pack of the Epson, so my testing was very limited for that particular paper. All testing has been done with gloss enhancer ON.
Over all I am very hopeful that this fix will permanently solve the problems I've had with these types of papers. I really like the Epson Exhibition Fiber, and will try more prints when I am able to find more sheets.
These fixes are in the experimental phase for now, and I have been assured that if better solutions are found down the road I will be eligible for them.
I must also add that my overall satisfaction with HP tech support has gone way up after dealing with their senior level support, and that the engineer that installed my new parts was very professional and determined to do the best job he could. I want to also thank Ben Wolf for his assistance.
NOTE: I do not believe that the pinch roll marks are related to the height of the star wheel assembly, but I tested this way because I was getting star wheel marks in deep blacks on all of these papers prior to the new star wheel assembly installation.