Your best bet to clean up your cartridge is to use either nail varnish remover (or similar) and a cotton bud....Hold the cartridge upside down and wipe until clean.....you can go at this quite hard.....clean off with a tissue......if this doesn't work then you may have just got a cartridgethat has reached the end of it's life as they can be refilled up to ten times but eventually the heads just give up and become clogged and lose all print quality.
Interesting how you suggest acetone to clean the heads, I thought most inks were water soluble and could be cleaned with warm water (damp cloth rather than running it under the hot tap).