[silkstone]

Just a thought Gary.... If you lift up the cover there's a foam strip at the bottom of the case. I believe that part of its purpose is to soak up waste ink when you do borderless printing and some ink sprays over the edge. I find that it can get quite saturated, so every so often I use some loo roll or kitchen paper to soak up as much as possible.

I don't know if that will help, but it's possible that the heads are picking up ink from the foam rather than being cleaned by it.