Buying a 4 Post Lift advice

Mine is a backyard buddy, 7 or so years of near daily use. Free standing with a wheel kit. If its a free standing one, floor needs to be pretty much dead level at the posts or it may move a little. Mine walks a little, and i need to move it back a couple tines a year. Daily use though.
I bought mine new off a buy abd sell site,$2500. Guy bought it at auction and his dad wouldnt let it in shop.