Laser print ghosting

[Hamlet5]

I have a Samsung M2835W laser printer which is 4 years old and has developed a print quality problem.

At the top of the page, text or a band of solid black print cleanly and evenly with no banding.

The black text appears 3.8cm further down the page as a white ghost on any dark background (i.e. as a negative image). It then appears again a further 3.8cm down the page as an even paler white ghost on any dark background.  This white ghosting of black print happens all the way down the page. No black print appears in the wrong place.

Is this problem likely to be caused by the imaging unit or the fuser unit or something else? If it is the fuser, how easy is it to replace?

Other info:

• The toner seems to be fully fused on the paper and does not smudge at all
• The toner amount remaining is 23%
• Impressions printed: 2150 out of a printer rated life of 9000 impressions
• No error messages

Thanks for any advice.

[Valsimot]

36,75 mm is the circumference of the developing roller inside the toner cartridge if you can try a different toner.

[Hamlet5]

Thanks for that info.  Changing the toner cartridge has fixed the problem! 
What strange symptoms though. It must have been a fault with the developer rather than just low toner.

Happily printing again.