Question : Why has my color laser printer started making a horizontal bars of heavier toner concentration across the page
It’s a HP 1500L, and I’ve had it for years.

Both the printer drum and toner cartridges were replaced a (low volume) month ago, and should not be even close to empty.

I’ve taken out all he toner cartridges and shook them a bit, to redistribute the toner, but this didn’t make any difference.
printer toner

Best answer:

Answer by duffaboy
Power off Printer and remove toner, look inside for a Black/Grey spongy roller which the toner sat on clean this.