We keep getting a grey band on the last 1cm of the

We keep getting a grey band on the last 1cm of the label on the newer TLP 2844. This is even with just doing a test print from the printer.
We have a lot of these printers on site and a few of them are displaying this problem. Tried different labels and even differnt brands of ribbons and tried cleaning the heads.

The older models are fine - the ones playing up seem to be the newer ones.