IMBs failing on MCS EAGLE 8540 INKJET System

We are having trouble printing out working IMB barcodes on our MCS Eagle 8540 Inkjet printers. This happens when we output our files as PDFs or AFPs; according to our staff, the IMBs print out looking choppy, and when running on our older printers, they actually make the entire system crash.

I attached a picture of an IMB sample from one of our AFP files. I noticed that the width of each bar is inconsistent.

Here are the specs we’ve been using for the barcode:

Any idea what could be going wrong? I apologize that I’m not able to describe the problem better, as these are printing to a remote location I can’t physically go to. But if anyone has an idea what could be going wrong, please let me know.

I haven’t used this method for creating IMBs but my first reaction is to turn off Proportional scaling.