problems with Scotchmark and laser printers

I sometimes use Scotchmark 3M 7883 labels and normally would print these in an
HP5L. The last batch showed inadequate image adhesion - if the labels were
curved during application, the image would rub off somewhat as the label was
smoothed down with a wiping action using a soft cloth.

Is this indicative of a fuser problem?

Also, on one sheet there were faint ghosts with a repeat interval of either 64
or 74 mm (+/- 2mm). Is this indicative of a particular issue.

To try and work around these problems, I despatched the image with my son to
print a sheet on his work's Fuji-Xerox high-end machine. Apart from the first
run being wasted due a fonts issue, the follow-up run (with fonts now embedded
in the document) showed the same problem with image adhesion quality. The
supplier tested the material at his end and found no problems, and even printed
MY image on a sheet which was part of a resupply order. That sheet was fine.

When two lasers exhibit a problem with the media but the supplier's machine
didn't, is it more likely there is a hardware cause or a media cause?