I don't know the 3070A printer but my searchings say it has separate cartridges for each colour. If this is so then it may be possible that the air inlet passage is blocked on the top of the cartridge thus stopping the ink from leaving the bottom feed. Check the top of the cartridge and peel back the label which covers a very fine inlet groove for the air, cover with the mouth and gently blow to see if any ink now leaves the bottom exit.
If still the same then either replace or return to supplier.
However, if the cartridges contains all three colours then place the cartridge print head in a saucer of hot (not boiling) water and leave to cool then gently dab dry with a paper tissue. All colours should show up on the tissue.
Repeat with hot water if necessary. As already suggested, clean gold contacts (also contacts in the printer) with Meths and leave to dry.