I have an electric seat up and down. Has two pull tabs to go forward and swivel. I first noticed a problem when the chair wouldn't lock back forward. As time went on the chair swiveled 180, locked and wouldn't go back straight all the way. I pulled the chair apart last night to reveal the mechanism and it's basically a turret mount with 6 flush hex bolts holding it down. Two bolts backed out not allowing the chair to rotate. My question: I tightened the bolts thinking they were just loose.... once i did this the chair wouldn't move an inch. Are these bolts supposed to be free floating? why would an engineer design it this way?? It's only logical with all the vibration a bolt will eventually free itself. Fixes?