Note, that if the threaded Post is loose or easily removed, it is an indication that the Post or  Mechanism and most likely both, need replacement. Mechanisms shipped are complete with Post, Washer and Bell which are factory installed. Some people in a cost saving effort, will attempt to weld the 1" Acme threaded post to the mechanism. This rarely succeeds as a permanent repair.

The Hub Liner is NOT part of the Mechanism assembly. It is a part of the Base assembly, and can be purchased separately. See Hub Liners for size and price description.

Scenario 1. 
To install 83B Plastic Thrust washer when Post is solidly installed into mechanism and machined keyway groove exits out of the post bottom.
 
Simply slip it on in-between the Bell and chair base making certain it fits into the Post machined keyway groove. Under any circumstance do not remove Post from the mechanism.

Scenario 2.
To install 83B Plastic Thrust washer when Post is still solidly installed into mechanism and machined keyway groove does not exit out of the post bottom. 83B Plastic Thrust washer should be saw cut as shown in page photo directly above the wording "#83B Thrust washer".

To install the washer, it should be twisted at the saw kerf so that each portion is facing an opposite up/down direction. This will allow squeezing it over the 1" Post somewhere in the middle of the Post length. Be certain to place the trimmed TAB into the keyway groove while installing. Under any circumstance do not remove Post from the mechanism.

Scenario 3.
The Post (replacement post) is not installed into the mechanism.

Slip the 83B Thrust washer over the tapered Post end making certain the TAB is inserted into the keyway groove and install the Bell.

The post is installed into the mechanism using a 40 pound blow.