Hi Mike; you depress me with your advice!!! - but thanks anyway; I'll bear the roller thing in mind. As I said, brick-karzi performance to date, except for the cyan cart.
And yes, it is the cartridge: I disabled the printer check, swopped the carts about, and still got streaks on the cyan. So that's that.
Reassuring to see you're still around: you've been a little silent of late...
And Cats: thanks for pointing me at the HP site - even though it kept trying to tell me about inkjets; I got to the right page eventually.