Heavy scratches appear on Heavyweight Coated Paper with HP Designjet printer

[StudentPrint]

Whenver we switch rolls to HP Heavyweight Coated paper and start printing, we get these awful gray scratches on the page. In the past it would clear up just after a few inches, but this time we have mostly-black image and it seems to have intensified as the scratches are appearing in about the same spot. 

My initial thoughts were that the printheads were misaligned or the paper as exremely warped. 

What I've Tried so Far

*Clean all printheads (both by hand and with the Clean Printheads function). This helped somewhat, as the PK and MK printheads had a great deal of solidified ink on them.

*Reseat and realign each printhead

*Try other types of paper: Scratches don't appear to happen with other paper like HP Everyday Pigm Stn.

Other information to note

*All of our ink expired long ago, and we've continued to use it for months if not 1-2 years.

*After cleaning the printheads, the printer indicates that only the yellow printhead needs to be replaced, not the photo or matte black printheads.

*Both our ink cartridges and printheads are out of warranty, according to the machine.

*We operate in an environment with about 8-10% humidity and 76 degrees on average. (We also have little to no control over this)

I would greatly appreciate anyone's input on this, as we've been experiencing this problem the last 6 months or so. 

[jasonmiamifl]

you should check if air inside inktube ?     remove printheads & use syringe to draw out ink.

do a dignostic print, if your printer has that option & make sure all colors ok...

if all ok... perform a     printhead alignment test & make sure it pass...

use   normal or best     print quality. also check paper & make sure not curl up / warp .

( my Z3100 44"   the tiny wheels   some areas are missing & has troubles to forward canvas to
print long image with dirty black lines. I have to straight up canvas after every big prints  ) 

I guess you might see result after above .....

good luck

[skuks]

It looks like printheads are sliding over paper (skidmarks on every pass through image) - paper may wrincle if vacuum isn't enough - vacuum holes may be clogged or must use another printing profile for heavy materials...we used to pull down the paper with hands for a while to compensate vacuum job...