I tape the factory covers onto the bottom of the cart while filling it thru a hole driled in the top. Then I dab a little silicone rtv in and over the top hole. The rtv is easy to remove for next fill.
You might also have pigmented ink built up in that particular connector.
Would be fairly simple to flush that connector with alcohol & water while exercising the gold fingers.
It is no too hard to disassemble the printhead down to the connecters that mates to the cartridges. There are 5 of...
1) Start by describing the printer problem in general that you want help in fixing.
My problem is the Pigment Black cart does not pass the nozzle test nor the service test print. It misses the lower half of the
nozzle test and some blocks of the lower half of the service test print...