Small ink dots on every page on Laserjet 4300

[printer]

On my Laserjet 4300 there are small black dots on each page. Not always in the exact same position, but in the range of around one inch they are on all pages.

Is it the toner kit? Or should I use a new fuser?

[redcow]

Run the half self test.
Put paper in the MFT and print the Config pages from the control panel.
When the paper gets halfway into the printer open the top cover. Pull out the cartridge and look at the page below. If it has dots on it, replace the cartridge. If not take out the fuser and look for the dots on the rollers.