Slide the wheels back on.
Hydraulic bar stool won t stay down.
You need to remove the seat to.
If the chair won t stay up even when no one is on it lay it on its side.
So the least you can do is to buy quality replacement parts.
One of the most popular gas lift options for bar stools works using a piston.
The height of the chair is normally controlled using a lever below the chair.
However the ideal thing would be to shop for higher quality.
This is where compressed air or gas is forced through a valve into the back of a piston which then pushes the height of the bar stool upwards.
If the plastic skirt covers the cylinder at this height you will need to remove the skirt first.
Most standard office chairs are controlled by a hydraulic or pneumatic lift mechanism that allows the users to move the seat up and down to suit their body shape and desk setup.
To do this turn the chair upside down push the retaining clip at the base with a screwdriver and pull off the wheels then the skirt.
Also note a quality gas lift bar stool is a very durable model and the fact that you are interested in how to fix gas lift bar stools probably means that you have downsized on quality when you bought your stools.