I agree with Ernst on this.
The only way to verify that there is a clogged line is to perform a bongo test (see repair manual) and that is a lengthy and arduous test.
Replacing the print head as you are prepared to do would be my recommendation.
Just a head's up: there is a slight possibility that you may have a bad cartridge. It is very difficult to nail down which one would be bad, hence the bongo test, but it could be a possibility. If, after you replace the printhead you still are having the same problem, you can look into one of your cartridges having a possible breach even if a minor one. If you have old carts, the likelihood is all the more possible.
All in all, my guess is that Ernst is right and it's a funky printhead.
BTW - cleaning fluid? That's a no-no.... If anything dial that back and use some Windex if you feel you must.
Best -
Mark