After doing utube videos, I finally put in the jack I have a 3.5 ton craftsman, I also have a 1.5 ton craftsman, I lost the manuals for both, lucky the little one had a sticker on the cylinder with a rubber plug, it says oil filler plug?? All the videos I watched guys were putting oil in the back were there is a steel screw. The video I found for mine also showed oil being put in the cylinder. I had tranny fluid on hand, and thought how am I gonna get the oil in there? Came up with the idea of using a 20cc syringe I think I put in 80 or 90 ccs. Jack is now lifting all the way up. I really hated to buy another, thanks for the help, glad I looked into it more and more. It really has been a good jack.