Canon MP530 doesn't print black

[danepak]

My Canon MP530 doesn't print black anymore.
I can print in cyan, magenta and yellow, but not black (I'm not sure how good the other colours print though - please see attached scan of test print).
I've ensured that both the small and the large black cartridge are both full.
I've tried to do a clean and also a deep clean, but with no success.
If I do a test print, the black does actually show, but it's very grey.
I've purchased a service manual on Ebay, but I'm not sure where to start and what to do.

Any help is much appreciated.

(I haven't got 25 posts or more, so can't post an image - please see image link below)
zealandmedia.com/canon.jpg

 

[aoife]

Sounds like the purge unit could be blocked. Getting to it is a big job however! If it turns out that is the problem after you've cleaned it you should run a nozzle check and head clean.

 

[danepak]

Yep, I realised
I tried to pull it apart, but just too complicated.
I'll get a new printer instead.