Thanks Beb, but tried that. Sorry - should have said. I am using 'Genuink'brand compatibles at present, cannot recall brand name I was using for my previous cartridge, but have used Genuink before without any problems.
My printer, by the way, is three years old. Is it usual for them to have near death experiences at this stage? I am by no means a heavy user.
The POWERFUL cleaning facility cleared my blockage (Oooer !!) on a Stylus Colour 760 which is three and a half years old with under average use. Black output was actually nil (100% blocked) until I used this. You can reset ink counters with it too.
Will investigate a cleaning cartridge. SSC, by the way, seems to be producing some results - I've gone from no black at all, to having about 25 percent strength on printer tests, after a few cleaning runs.