Thanks for your message. The solutions you suggest were also given by online support and have not been successful. The cartridge has worked fine from its installation (from HP Instantink) until this fault started. Can I request a new cartridge from Instantink? If so, how? It's actually very difficult to communicate with HP.
Has anybody else encountered this cartridge problem?
Error now temporarily resolved (printing with colour cartridge only) pending delivery of new black cartridge via Instant Ink. But why was it so difficult to get that help - eventually finding a real person to interact with?
However thank you for your offer of help, now not needed.
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