Michael Chare wrote:

My Dell C1760nw laser printer no longer wants to print labels properly.
Instead of all the ink sticking to the paper properly first time some of
it gets left behind and then printed lower down the page

One supplier of 3rd part toners suggests "Gently slide the green tab of
the drum unit from side to side several times to clean up the corona wire."

Dell's troubleshooting section suggests using their toolbox to increase
the fuser temperature.