what's the deal with the grease pumps? how expensive are they and do you remember what type were you using? any other thoughts?
I got mine free from Screen Printers Resource out here in Cali way back when with an agreement to buy ink only from them.
They are referred to as the "South Swell" pumps named after the company who made them. They sell for $125.
They start as a grease pump like this:
http://www.mcmaster.com/#grease-pumps/=cifv6v
You remove the existing piping from the head and get two 90 reducing elbows with a male and female thread. 1 to fit the threads on the pump head, 1/2 to 3/8 reducer and a 3/4 to 1/2 reducer. Twist one into the head, then the other into that one, then a 3/4 pipe that extends a couple inches past the edge of the top threads into that one.
http://www.mcmaster.com/#iron-and-steel-pipe-fittings-and-pipe/=cifx1d
The final part is the ball valve. If you know or have a machinist friend, stop and pick up a 12 pack on your way to see him.
http://www.mcmaster.com/#ball-valves/=cig3ywThe trick to the valve is you have to cut the front off (all the threads basically) until you just touch the inner face w/out cutting into the plastic behind it. This lets the ball close on the ink with a cutting action so you can squeeze the lever, build up a little pressure, crack the valve and squish out .01 worth of ink. The cut-away model shows that face and plastic. Getting that right makes all the difference. You can close the valve, swipe the face with your metal mixing blade and it's virtually zero clean up.

Had I a picture.. oh well,,... ya'll can figure it out.
The pumps work great for basic colors but when used for thick whites, they tend to blow the seal cup out the bottom. Use the graco style piston pumps for heavy whites.