Hello Everybody!

Have to refill an HP C6602 cart which is a scanner imprinter cartridge.
On refilling gives a swab test OK and than the swab impression disappears, Am lost.

Giving the cart a hard shake with the print-head facing down gets the ink back only to disappear after a few swabs.

Used ink that we refill the 818 black with.

Guys ps help as this cart is not easily avl.