A backless bar stool that gets a lot of work, tends to develop wear and tear problems over time. If it has moving parts, such as airlift or swivel, those parts will become worn out with a lot of use and need replacing. This is a simple job to do. Here is the procedure to fix the two most common mechanical problems; a broken swivel, and a broken airlift cylinder.
Part 1 - Replacing the Swivel
Step 1.1 - Remove the Swivel
The swivel is an important part of a bar stool. A broken swivel cannot be repaired, you will have to replace it. The swivel is worn if it makes grinding noises, wobbles, or even if the bearings fall out.
Removal is easy, you just remove the bolts or screws holding the swivel to the seat, and to the base of the chair. Occasionally you may come across a swivel that has a round access hole. You need to insert a screwdriver into the hole to remove the fastener.
Step 1.2 - Buy a New Swivel
If your bar stool has a back, you need to find out if the swivel is flat or tilted before you buy a replacement. This is not an issue, however with the backless as they don't need the tilt. Before you remove the swivel, measure from the floor to the front of the swivel, and again from the floor to the rear of the swivel. If the two measurements are equal, the swivel is a flat one. A tilted swivel will be slightly higher at the front.
Buy a new swivel. Take the old one to the store as a reference. The plate size of a new swivel does not need to be exactly the same size as the old one but if the screw hole pattern, measured from screw to screw, not diagonally, is the same, you'll save a lot of modified drilling and fitting. Buy a heavier 7-inch plate if it will fit. A 6-inch plate will be made of lighter gauge steel and will be thinner. A thicker one will stand the weight of heavier people better.
Step 1.3 - Replace the Swivel
Replace the swivel making sure that the pivot axis of the swivel is in the exact same position as before. If the new bolt pattern doesn't match, place it in its rightful position and mark the new hole locations on the base frame, then on the underside of the seat before proceeding to drill—for either bolt holes through or pilot holes for wood screws. You can then finally put the stool back together as it was. This is a simple job that will take only a few minutes.
Step 2.1 - Measure the Cylinder
Measure the broken cylinder. Do not include the pencil-sized piston rod at one end when measuring. You only need the main body length. Buy a new cylinder.
Step 2.2 - Remove the Stool Base
Remove the base of the stool by removing the base retaining clip and washer, located under the base.
Withdraw the lower portion of the gas cylinder from the base slowly. There might be loose parts in the tube that must be replaced later in the right order, so this may be the right time to pull your phone out and take a few relevant pictures as you proceed.
Step 2.3 - Remove the Cylinder
Make sure the rubber bumper or bearings and washers are not torn or worn. Replacements for these parts are available. Place the wrench on the main body of the cylinder nearest to the control mechanism while it is attached to the bottom of the seat. Twist the wrench in either direction to loosen and remove the cylinder.
If it's very tight, the mechanism may have to be placed in a vice, but avoiding to squeeze the hollow section of the tube toward the center or the open end. You should also wrap a few layers of electrical tape or duct tape around the section of the cylinder where the vise and some other wrench will come in contact with it, to avoid damaging it with teeth marks.
Step 2.4 - Insert the New Cylinder
Just hand insert the tapered end into the mechanism. Weight on the stool will fix it into place.