On Wed, 5 May 2021 09:35:06 +0100, ss wrote:


Samsung ML-2240 laser printer.
I have measured the ghosting image and it repeats every 38.2 mm which
would be approx a roller of 12.16 diameter, all of which I have
previously cleaned.


According to the service manual, the following distances for
horizontal lines apply:
OPC Drum 75.5mm
Charge Roller 37.7mm
Supply Roller 47.5mm
Develop Roller 35.2mm
Transfer Roller 46.2mm
Hear Roller 63.9mm
Pressure Roller 75.4mm

The Charge roller is nearest to your measurement. It seems to be
inside the toner cartrdge. If the lines are only 3cm wide, perhaps
toner is dropping onto this roller. It says typical defect for this
roller is "Black spot".
--
Dave W