Years ago I had one fail and I discovered just about a month ago you can repair them. The rubber o-shaped doughnut thing in there goes bad. First, you may have to grind off the pieces holding the inner washer/rubber doughnut thing in place. I did. Once you get it off, thread the rod for a 3/8" nut. Then take the top of your grease cartridge (the nylon plastic top) off and carefully and slowly cut the overhanging part off...you want to cut the top so it has the same diameter as the inside of your grease cartridge. This is not as easy as it sounds. Take your time. Then when that is done, cut a hole in the center about 3/8" diameter. There is a metal bonnet over your rubber doughnut. Re-use it. Mount the top thing you just cut upside down...you want it to catch the grease and push it up. You'll see what I mean when you do this...one way will let the grease get pushed past easily and the other way will sort of catch the grease as it goes up. Bolt it down and now...the important part...you will forever have to install your grease cartridge in upside down. You won't be able to push the new thing you made past the metal piece, but it will go nicely into the end that you took the top off of. I don't know how long this repair will last, but I didn't have to discard a perfectly good grease gun. Supposedly there is a place in Taiwan that makes a replacement rubber piece for these but I have not bought one. Good luck.

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end