Uncle,
I will assume a full cart, non plugged vent, sealed fill hole, no air bubbles, fresh ink and daily printing of something.
Do a nozzle check printout. I suspect you have one or more of the openings in the black head plugged. This will be evident by missing lines in the black and other colors of the printout.
Plugged nozzels can come from any number of places but mostly dried ink inside the system sloughing off and traveling to the print head is the culprit.
There are head cleaning systems/chemicals on the market. Some folks suggest hot water and some Simple Green in a spare cart running a bunch of one color prints...........
Others suggest to hit the ink button, allow the heads to come to the opening where we remove the carts. This releases the heads and you can easily move them, lay a folded paper towel in the trough where the heads travel, saturate the towel with Simple Green and slide the head assembly over the towel repeatedly. Repeat until the towel is clean. Replace it with another one, saturate it with simple Green and park the heads over it overnight. CAUTION....if you aren't careful the paper towel could become a permanent part of your printer. DO NOT make the folds too thick.
Remember you are dealing with RUBBER and PLASTIC. Harsh cleaners and solvents will insure you the purchase of a new printer.
There is a filter of some type in every cart. Some have sponges, some have fine mesh screens in a small circular area visible thru the side of the cart. These filters are designed to trap debris.
The exit "O" ring assembly at the bottom of the cart is a combination of an "O" ring, a spring and a stainless steel ball. You can sometimes recover a contaminated cart by GENTLY inserting the plastic tip, NOT the needle, of a syringe into the "O" ring and drawing out the ink. Then start filling the cart from the "O" ring with warm water. CAUTION, you WILL begin to squirt ink out the fill and vent holes in the top of the cart. Warm water and lots of effort will eventually give you a clean cart.
ken
