Remove and install a COM type gas cylinder

A standard common gas cylinder diameter is 1.102". For quick reference, it is a little more than 1 1/16" and a little less that 1 1/8". The 2" diameter Black part is NOT the cylinder. It, simply supports the cylinder and is called a Column.

1. Using your own Plumbers Pipe wrench. (Longer is much easier) 
2. Rent ($6.50) 21 day rental. cylinder removal tool.

Begin by laying the 5 leg and caster wheel base assembly with chair and gas cylinder up-side-down on a work table so that you can see the base retaining clip  and washer  located in the center underside of the base. Spread some newspaper on the floor to prevent soiling when it drops to the floor.

Squirt a couple shots of WD-40 (it's helpful) in the joint where the column protrudes out from the chair base bottom.

 While the base is up-side-down, place 2 or 3 legs (for support) on the work bench edge as close to the column as possible, and with a steel hammer, hammer out the column from the base by hammering on the protruding thin edge of the column with medium hard blows...it will remove. The chair will drop to the floor, so watch your feet! Set the base aside and wipe out any WD-40 residue with a rag.

 Then using the wrench and WD-40 or removal tool and WD-40, remove the cylinder from the mechanism attached to the bottom of the chair seat. Wipe out any WD-40 residue.

 Installing the COM cylinder

 Hand insert the plastic button end of the COM cylinder into the mechanism. Just simply shove it in! Now take the 5 leg base assembly and slip it onto the bottom of the COM.

 Turn the chair over and sit in it once or twice to tighten the taper fit.

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