Digital BW, The Print

Since a few days the 2100 spills drops and big black spots of ink over
the paper while printing. Sometimes more, sometimes almost less, but
rarely not at all.

As the printhead in the 2100/2200 is less easily accessible than in
older Epson printers, what could I do to find out what it is? I've
already put a piece of folded paper unter the printhead and manually
let the printhead go over it a few times, there was kind of inky dust
on it, but it should be gone by now, but still it spills ink...

Thanks, Bernie