I'd picked up a nice HP DJ 800 from a lovely couple from Windom who traded it in on a newly refurbished model. They'd said that in full disclosure they'd hired someone to replace the belt and after that repair the darned thing started popping up an error message they couldn't get rid of and they just wanted to NOT deal with it anymore. Thinking I'm the Plotter Princess of Lindstrom MN and I can fix anything I plug it in and instantly get the 21:10 error code. I take out the service station, disassemble it and clean it up and put it back into this lovely machine and darned if it didn't error with the 21:01 again. I tried another spare service station...it continued to give me the 21:10 error code throughout the evening and into the next day. I wasted a whole day changing the encoder strip and other hopeful things...and yet no relief. I was ready to scream when I stepped behind the plotter to plug it in one more time and noticed some pink insulation near the hole that's under the cover...see the pictures below for the rest of the story.
Yup, a mouse had been nesting in the HP Designjet 800! I'm sure she chose it because it had mousey sized holes and no human would ever bother her and the little growing family! The only thing that runs through that space is the ribbon cable...nothing else. The only reason I came to the back of the plotter to look more closely was because I'll read about on the HP Designjet Forum how that cable getting pinched can cause the 21:10 error code on the Designjet 800 and the Designjet 500. When I saw the ribbon was free of crimps I started to think about where the cable goes and looked at the little mouse holes! Mystery solved! Popped a new ribbon cable on this fine machine and instantly it asked for paper and ran a printhead alignment!