You're sure it's not the ink cartridge, I presume?  I've kind of given up on ink jets because of this kind of problem. Even new cartridges can clog if kept on the shelf too long.

The usual answer to a clogged print head, after making the kind of effort you have, is buy a new one. Another reason to hate ink jets.  Good luck though.

I can swear there ain't no heaven but I pray there ain't no hell. _ Blood Sweat & Tears