To remove the base, first remove the single screw located on the Bell. Then place the chair in it's normal upright position, grasp the chair back from behind and jerek it upwards once or twice to separate the base from the chair. Alternatively, push the chair over onto the front seat cushion edge. Then grasping the base, twist and pull to remove the base. When separated, inspect the Hub liner to insure it has not worn, cracked or broken. A worn liner will be rough on it's inside walls. If it looks or feels like it has threads, it is worn! Hub liners do NOT have threads. Worn, cracked, broken hub liners will cause much rocking and wobbling.

Installation of a manual base is just as easy as removal. With the chair still pushed over, simply place the new base onto the threaded post and push it up to the bell. Reinstall the Phillipa screw earlier removed from the bell and snug tighten to complete the installation. Lubrication of the threaded post is not required, but a light wipe of Vasoline inside the hub liner will not hurt.