Still here.
Both my 3880's are still running well ( 6 years later since this post began, and maybe now 12-13 years old and still both are working! ). Just I make double certain any heavy-weight paper has been de-curled on a PVC pipe as best as possible. I also NEVER use the matte black ink - or any paper setting that can call it into play - to avoid the ink changeover valve leaks. I just stick with a dark photo black for now (Jon Cone's InkJet Mall HD pigment photo black.) in the reusable carts.
I never got the service software or found it. I did use the feeler gauge mentioned earlier to set the printhead's height up (To-and-fro, and side-to-side.) which seems the most important. Just visibly looked all the other possible adjustment points for comparison and miked any that I thought may need adjustment. Don't know if the software is an absolute requirement from the OEM factory's initial adjustment.
I did get a friend's 3800 that blew out the problematic "Photo black/Matte black ink" changeover valve. I ordered a couple of them for about $20 each, but they look to be another major tear-down job to change out. Tell-tale sign is dragging black ink over the print at irregular times. Might be able to clean the printhead's underside once and get a good print or two before the valve leaks the ink again. Since I no longer use that valve with matte ink, it may have sealed itself into a not leaking position - I hope.
It takes a lot more time to get into the guts of this printer and why they easily say "Beyond economical repair" when it breaks. Least both of mine have run a lot longer than they probably should - albeit some nozzle misses which often cure after a cleaning or two and sitting a while or overnight. The "dye ink" 3880 seems to be the least plugging of the two I have, while the 3880 may plug a magenta nozzle in a couple of weeks of non-use. I should shoot some 99% alcohol onto the capping station pads to keep the ink from gumming up the capping station's pump motor and tubes, and maybe sticking to the underside of the printhead too, as I discovered when I tore into the thing.
Good luck with your repair and take copious notes and photos.
W.F.