Ziggy - I can't reply to your private message because I need 5 posts before that feature is unlocked for me. ?? :/ So I'm replying here.
I contacted Canon who had nothing of value to offer and who tried to sell me their "after warranty expires maintenance program." No thanks.
I found a...
The PGBK in my MP500 is doing EXACTLY the same thing. My nozzle check looks exactly like the PGBK line in block 3. of the image ziggy posted. I have cleaned/soaked the print head thoroughly but have had no success. It is as if 1/2 the PGBK jet has simply stopped printing.
If I may tag on to...