Give what cpicton1 stated a try. If that doesn't do it you'll need to open it up to get rid of the air pocket thats most likely sitting next to the pickup hole.
I've had the same problem w/ a decent Lincoln grease gun. Cracked the Fill screw on the head, burped it, and good as new. Frustrated the *%$#@ out of me until I figured it out.
Save up your pennies and buy a bulk greaser like me. We have a lincoln that fits a 120# open head pail. You hook it up to shop air and grease away. The delivery hose on mine is 25 feet and the thing is on casters. When I got this unit, I threw away all my cartridge guns. One pail last me about 2 years and that's greasing all the haying equipment, tractors and vehicles.
Well Richard, it's been a few days since you posted about the problem you were having with your grease guns. I am just wondering if you have tried any of the suggestions given to you and if any of them worked for you? We like to be updated now and then when a fellow TBN'er is having problems. /forums/images/graemlins/smile.gif
Aside from bleeding, I open the handle fully so the little ram inside is back to push the next shot of grease, then holding the gun upside down tap it on a tire to shake the grease into the void and pump it from time to time until the grease starts coming. By tapping I mean vertically downward not sideways, with the handle open, this generally works for lme.
I have a push button and some kind of other thing with a small ball in it you can push in like a tire valve. Niether of these had any affect. I pulled the rod back, took off the top and pushed the rod up intill the grease was about .25" over the top. Screwed it in and it worked well. Only took me a few seconds but I sure would like to know what those things on top are for /forums/images/graemlins/confused.gif
<font color="blue"> I have a push button and some kind of other thing with a small ball in it you can push in like a tire valve. </font>
It is for filling your grease gun with a Bulk Grease Gun Filler Unit, such as the one pictured.
The next time you put a new grease cartridge in your gun leave the top loose until you push the bottom plunger in enough to have grease start coming out around the threads. If you do it that way you shouldn't have any problem. /forums/images/graemlins/smile.gif
Like Craig said, the valve is for filling the gun with bulk grease (if you have the right dispenser to do it) and the other push button is just an air release. Even with the gun completely screwed together, if you hold that button down while pushing the rod in and out a couple of times, you'll usually expell the air that keeps it from working right.