DesignJet 130NR not printing colour

[grmnsplx]

I just picked up an old - barely used - HP Designjet 130NR. It had been sitting in storage for years.
Anyway it seems to not want to print any color. It prints in grey scale but it's pretty banded.

I tested a print job on the roll and it printed, but only in black and white.
I then ran the diagnostic test print and it had a little color - very little.

I then cleaned the printheads (85) by placing them on a damp paper towel and then let them dry and reloaded them.

The light magenta was giving me errors so I cleaned the contact in the printer and it checked out fine.
I re-ran the diagnostic test print and there was no color at all (just black), and afterward the light cyan was showing an error. I took that printhead out and I can see that it's wet with ink. So it's weird that the ink is coming out but not being sprayed onto the paper. I cleaned that one up and the error went away.

The cyan (regular) print head was also wet with ink. Also, I can see that ink has dripped inside the printer under the printheads. So it seems to me that something is kind of working, but obviously something isn't right.

Some of the ink levels are low (magenta and cyan (regular)), but not empty.

I ran the cleaning with the software utility and it produced some diagnostic prints. The first had a little color, very faint, but the last two were just black and white.  

Is it possible that the ink is old and viscous? Should I just replace all of the ink cartridges? Should I replace the printheads. Is there a better way of cleaning them? 
Getting new third-party ink is economical. but replacing the printheads is not. I'd only do that if it were guaranteed to work.

Any advice would be helpful. Thank you.