It has been some time since I have had to change the grease cartridge in my grease gun and after replacing my old one I can not get the gun to work. I opened the gun up and took out the old one and pulled the spring and plunger in the base back and locked it in position. I then inserted the new cartridge, and released the mechanism that pulls the spring and plunger at the base of the gun. How ever I can not get the gun to pump grease. I also can not get the bar that pulls the spring and plunger back to pull them back. It just moves back and forth freely - while the spring stays extended. No matter how much I pump I cant seem to generate any internal pressure in the gun. Like I said its been a long time since I had to do this and I can not figure out what I am doing wrong. Worse part is 5 minutes of messing with it and you can not do a damned thing cause your hands are to slippery from the dammed grease.