Spread newspapers on floor to prevent greasy falling parts from causing stains

First turn the chair up-side-down so that the  and  in the center of the base bottom underside can be seen.

With a screw driver or needle nose pliers, lift up the holding clip upper portion only from the piston rod tip

Withdraw the base while pulling and turning. The base will easily remove from the gas cylinder most likely pulling with it (hidden inside) the 2 washers and ball bearing. Set these parts aside to be reinstalled with the replacement base. There should be 4 small parts. If not, look inside the withdrawn column the remaining part(s) where usually you will find a washer at the bottom.

Installation and bearing kit information
To install or replace a base, first replace the rubber cushion onto the piston rod, pushing it as far up as it will go. Then the large washer, then a lightly greased bearing and lastly, the other large washer. Wipe off greasy hands on the gas cylinder body. Now, slip the base with hub column up onto the gas cylinder. The remaining small washer and clip are then lastly installed onto the protruding piston rod end at the outside bottom of the hub column (see schematic below). These six small parts can all be easily replaced using our very low cost bearing kit #108 with printed schematic.