HP 16500B Pattern Generator (16520A) will not load files

[pnv57]

I recently added a pattern generator and expansion (16520A and 16521A) to my HP 16500B, and a big draw for me was the fact I could build programs for the pattern generator on my PC, then load them up via floppy disk. When I tried to load the file (via the merge function in the listing editor) it says "File not found". I can save the listing to the disk, but I get the same error when I try to load it back. The file clearly exists, I can see it in the hard drive browser, and I can load it back onto the floppy and onto my PC. I'm on the latest OS (3.14/3.13 for the mainframe, 3.03 for the pattern generator), I tried 2.03 (2.00 for the pattern generator) as well. In addition, I tried to load the pattern generator 1.00 software from the C mainframe and the 2.00 software from B v2.03, and then edited the files to make them appear as the 3.03 version. None of this worked. I have a 16500A as well to try to test it with, except the front floppy drive is misaligned currently, and I am working out how to realign it. The service manuals don't appear to be much help either, as they don't explain how anything works, other than vague block diagrams. Has anyone else run into this before? Any suggestions?