Simple cleaning tip. Run several sheets of plain paper through it. By reversing and flipping, you will get 4 passes for every sheet. What might have happened, ( I notice Adobe PS mentioned) is that you have printed borderless pictures which often bleed ink into the machine, as the image is slightly larger than the paper on which it is being printed. A good way of avoiding this in PS is to get your picture up and then open a new file at A4 or whatever (in the drop down menu) and using the "Move" tool, transfer your pic to the new canvas, resizing exactly. It is a doddle.
If you can get to those rollers and the platen, cotton buds with alcohol work well. you will be relieved to hear that Scotch doesn't work and in fact makes it sticky, so just use that stuff for swallowing. Chemist will give you a bottle of the right stuff for threepence.
Conan