I'm hoping that your advice will save me having to take the printer to the Canon-nominated repair facility, which is what Canon have recommended.
The ink cartridges and print head all seemed fine. I wiped away a little surface ink on the print head, but it was a very small amount.
BTW, printer is out of warranty.
Hi Freddy. Followed all your instructions. It took about 8 rinses for the water to be clear. Made sure print head was dry. Reassembled and restarted, but error message still the same. Switched off and unplugged printer; left for 30 minutes; restarted, but error message still the same.
Still the same U052
I've checked out buying a print head, but they're almost as expensive as buying a new printer! So that doesn't seem a very good idea.