I have used rubbing alcohol through a drinking straw used as a pipette to good effect. You just centre the printhead, remove power, remove the print cartridge, and apply the alcohol. No doubt other substances would do the trick. I read somewhere of the use of vinegar, but have not tried that myself, as I reckon that something that evaporates is ideal for the purpose.

Blowing through the straw also has a good effect in conjunction with application of a solvent.

It is simply done.