Hello wise ones. We replaced the print head, and ran 2 or 3 nozzle checks and cleans, which allowed us to print one good sheet before the print quality reduced again. I tried to run another nozzle check, but it didn't work, I suspect because the waste ink tank is full (we had the error message about this the previous week, and reset it). I switched the printer off, and tried to switch it on again, but it's as if the power button no longer works. I restarted the computer and tried switching the printer on, but no joy. I reloaded the printer driver, again no joy. We unplugged the printer from the mains for a couple of hours, and switched it back on again, but yet again, no joy. We're currently in the process of removing the waste ink parts to clean them before trying again, but the question is, would the waste ink tank being full, prevent the power from coming on? It feels to me like we have somehow been locked out of switching it on. We appreciate your help and advice very much. Thank you.