DesignJet T120 not printing accurate size

[skinny01]

I'm using the designjet t120 to try to print patterns from Illustrator and it isn't printing to accurate dimensions equally. 
I'm on 18x24" paper being sent through in portrait mode. 

I've tried the standard tactics of printing with no scale at all, and also setting the scale to 100% in case there was some translation issue.

My dimensions are accurate horizontally across the 18" side but lengthwise dimensions in the 24" direction are coming up short almost 1/8" for a line that spans the total length.

Any ideas on how to fix this or some other setting I may be missing?  I'm sewing with these patterns where multiple parts all have to come together accurately and that's impossible with the dimensions varying this much and that's the whole reason I got this printer.

Thanks in advance for the help.

[Repairatrooper]

Run any calibration routines that the printer offers, printhead and paper advance.