Thanks for sharing your Happijack experiences. My jacks have given me grief for a few years; really noisy, non-sychronized lifting and getting stuck. Tried to get professional service this year and all the shops are booked until the end of August. I did recieve great advice from one service provider suggesting the tube and shaft could be rusty. Then I found this forum which led me to a link for taking the jack apart. Genious. I'm on jack#1 and found a shreaded "O" ring hanging on to the screw. Looks like it came from where the screw meets the top of the leg. Can't find details regarding the size of the "O" ring. Any suggestions?