Many office chairs with the capacity to rise, lower and swivel feature a pneumatic cylinder. Over time, leaks or excessive use can damage the cylinder, causing the chair to either lock in one position or slowly sink during the day. Instead of contacting the manufacturer for a replacement cylinder or chair, you can take several simple steps to salvage your chair from the dumpster. If your desk chair is wobbling, but still changes position vertically, it is most likely a problem with the wheels or base. Tighten all screws and check the wheels for uneven setting.
Check the pneumatic cylinder's position. If the cylinder is locked in place and will not rise at all, most likely an essential element is broken. The best solution is to replace the cylinder or secure the chair permanently in the desired position. If the cylinder touches the floor, the problem may only be a missing washer or spring clip. Contact the manufacturer for a replacement. If the cylinder slowly lowers over time, the problem is most likely internal and may be fixable by dissembling the chair.
Sit in the chair and determine the desired height for your desk. Measure the distance from the base of the seat to the floor, and make a mark where the cylinder falls in this position. If you'd rather have the chair locked in the correct position, use a drill to make a small hole through the entire shaft and insert screws into either side.
If you don't have access to a drill, you can also lock the chair in a raised position with wood and duct tape. Some suggest using parts of a yard stick. After moving the chair to the desired height, break or cut the yardstick pieces to fit snugly between the wheel base and seat. Secure with several strips of duct tape to hold the seat in place.
Dissemble the chair completely using a Stillson wrench. Lay the chair seat-down and remove the clip and washer and the centre of the base, depending on the model. Remove the base slowly and check for small parts. Next, place a Stillson wrench on the main shaft and turn in either direction to loosen.
Tighten the screw at the top of the lift to control the air pressure and reduce leaking. If you find an issue with the piston, you can use copper piping to replace a broken or bent piston. Then, reassemble the chair including all pieces.
Using a cloth between the Stillson wrench and the chair shaft may reduce scratching and scarring. A lubricating or water-displacement spray may loosen the chair in order to disassemble or for further use.