HP 6520 prints black on print quality diagnostic page only

[ChunkyKitty]

Ahoy-hoy!

I ran through all the HP cleaning, replaced full ink cartridges with new ($$), and when I print I get either very faint black or no black. The print quality diagnostic that follows the cleaning is clear, except the black box is empty (although the border prints). 

I realize this printer is a bit old and out of warranty but I just purchased new ink (based on the recommendations in HP troubleshooting). Somebody please throw me a bone and tell me I didn't just throw good money away? 

[8lives]

You have a blocked black printhead, you can try to clear it manually.

Search youtube for vids on this subject.

[ChunkyKitty]

Thanks, 

I had found and tried the one with a solution of hot water, paper towel below, and on the print heads to no avail.

Last night I tried another where you use a syringe and straight alcohol, I let it sit overnight but still, the black box has a band but no fill. It's weird that the characters print in black, the borders on the boxes print in black on the Print Quality Diagnostic but nothing else.

I'm going to try the alcohol/syringe again today.