So I stopped using my 1500W daily as I was testing another printer. I still sent a few test prints here every couple of days to keep it happy. I've now found the black head is completely blocked! Inktec inks so I'm really surprised. All other colours are giving perfect nozzle check. I've put other carts in to prove it isn't the CIS and tried usual cleaning tricks but I get nothing, absolutely nothing. Seems so strange, normally you'd get something showing but black channel not there!
Gutted as it's not had a great deal of work through it since buying new, just small regular jobs.
So if I can't get it working (which is looking more and more likely) I'll have to look at a different model unless I can secure another 1500W from somewhere (emails sent to a few sellers!)
Failing that, anyone interested in buying it that may have better skills than me to clear the head? Or even for spares as it's otherwise spot on :-(