Canon Pro-300 won't print after ~6 months of being in storage

[earlyadopter]

I have Canon Imageprograf Pro-300 which was sitting unused for about 6 months. It worked before. It does not print now.
Everything that is supposed to – moves inside, but the paper comes out blank. Tried "Nozzle Check", "Print head cleaning" (both cleaning and deep cleaning) multiple times.
Replaced all the ink cartridges.

Buying a replacement head looks like an expensive next step.

Are there any other tests or troubleshooting suggestions I should try before spending ~$400 on a replacement head?

 

[Artur5]

You should elaborate a bit more.

What kind of inks are you using .. Canon original or third party ?
Nozzle checks come totally blank or there’re traces of some colors ?
In the later case, did you see improvements, albeit minor, after each head cleaning ?

BTW I hope you didn’t perform several deep cleanings in a row, that might have killed the printhead

 

[earlyadopter]

@Artur5 inks are third party, refilled original containers. Never gave any problems before.
Nozzle check leaves no traces of color on paper – it's as blank as it goes in. No changes after 3 or 4 cleanings (at least 2 deep cleanings).

I didn't know I wasn't supposed to do more than one cleaning when it didn't produce any visible results.

 

[The Hat]

I didn't know I wasn't supposed to do more than one cleaning when it didn't produce any visible results.

Try soaking the print head in 2cm of warm water with a good squirt of Fairy liquid, and leave it there overnight, then in the morning thoroughly dry the head by leaving it somewhere warm for a few hour and then try another nozzle check..

You should get some if not all the colours returning…

P.S. Try flooding the purge unit with window cleaner just before installing the head again.. Yes only one deep clean at a time every few hours..