Like you Clive, had 2 myself.
Now have a Laser jet for doing mundane work and a Canon IP4300 for doing Photo's.
I did open up the epson to see why it came up with the messages after googling the said problem and as the Pictures show my sponge was caked in ink
found out that if you take out the little pipe from the back of the printer and clean it out ..the messages stop
but be aware make sure the pipe doesn't flap about or you might get ink all over your desk top
Si, all that black ink is a mixture of all the colours put together ....
with the black being the dominant colour it tars all the other colours.