Hi everyone,

I have several height-adjustable bar stools like the ones shown in the attached photos, and they have developed the same problem.

The stools use a lever underneath the seat to adjust the height. When I pull the lever without sitting on the stool, the seat rises normally and can be adjusted to its maximum height. However, once I sit on it, the mechanism does not seem able to hold the pressure/height anymore.

Under my weight, the seat gradually sinks until it reaches the lowest possible position. If I stand up and operate the lever again, it rises normally, but the same thing happens as soon as I sit down.

The stools are otherwise in good condition, so I would prefer to repair them rather than replace them.

From what I understand, these stools probably use a gas-lift/pneumatic cylinder similar to an office chair, but I have never disassembled this type of mechanism.

I would appreciate some advice on:

• Is this symptom usually caused by a worn or failed gas-lift cylinder?
• Could the adjustment lever or valve mechanism be keeping the cylinder slightly open instead?
• Is there any practical way to repair/recondition the existing cylinder, or is replacement normally the only solution?
• Are these cylinders generally standardized, or would I need to measure the existing one before ordering a replacement?
• What measurements/specifications should I check to find a compatible replacement?
• How difficult is it to remove the old cylinder from the base and seat mechanism without damaging the stool?

I have several identical stools, so if the cylinders are the problem, I would ideally like to repair all of them rather than replace the entire set.

Photos attached showing the stools, adjustment lever, base and central column.

Any advice on diagnosing the problem before I start taking them apart would be very helpful.