A broken rear bushing can be an issue but the solenoid that shifts a wedge on or off the rear bushing for the head height switch can also be a cause for that problem. When I print on the 350 grams Museum Etching I see that the wedge is not completely shifted to the left for the highest position and there are smudges on the paper like you see. I have made an arrangement that I can do it manually. It is seldom that I print on thin papers but in that case I bring the solenoid lever downwards again and let the printer shift the wedge for a lower height. Maybe a crude approach but it suits me. If the printer has to be initialized again it may sense that the solenoid does not properly and I have to bring that lever down too.
At least if you have removed the right panel to clean the service station then you could also take out that light grey "pen, knife, spare cartridge" compartment and check the movements of the solenoid-lever underneath it when the machine is initializing again or after thick and thin paper setting changes. You can insert that compartment again with the cover already installed, it is not symmetric so keep an eye on its shape.
Met vriendelijke groet, Ernst
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