If that pic is what I think it is, your jack has no grease fitting. As lame as it sounds, my jack that came with my trailer did not have a grease fitting and the only way to lube it was to take that plastic lip off the top and shoot grease down in there. And ya, it looses it really fast. And the wheel would normally only lock into place if it was jacked up all the way. Then it would jam big time. Get rid of the jack and buy one that has a grease zirk so you can maintain it, that is if this is what you have. Good luck dude.