The other day I sought advice on cleaning the printer head on an
older Canon machine. The response was to various web sites and
discussions.
I didn't see my first reply - wading though the digest sometimes and
short msgs can be missed. Here it is again.
I solved the problem with a solution of isopropyl alcohol ( used in
windscreen washer products) and an ultrasound bath (optician style).
A few minutes of that and some fiddling with head cleaning once
re-assembled and a document with bars of red, yellow, blue and black
and - back in business.
Probably little point in soaking for days - soapy water - detergents
etc. Enzyme based detergents might be OK.
Also might be a bit messy with printers that have the electrodes ON
the cartridge.
Bill