We tried to replace the pneumatic cylinder in our Office Depot Quantum Mesh Chair manufactured by Raynor Eurotech, but it was hopelessly stuck in the base, even after several days' soaking in WD-40. Customer service recommended pulling the "pin," which looks more like a clip, from the base of the stuck cylinder, but didn't have pictures. So here are the pictures and the instructions. /watch?v=uiDby4FouwQ) to get a general sense of what you're supposed to do. Customer Service recommended this particular vid. 2. Of course, it looks easy in the vid. But the bottom of the cylinder can be hopelessly stuck in the chair base. Customer Service recommended pulling the "pin" straight out from the bottom of the stuck cylinder. In reality, it had to be pried and pulled (and destroyed in the process) with a screwdriver and pliers. 3. Once the pin is off, the gas cylinder comes apart fairly easily and the chair seat with the top part of the cylinder separates from the chair base with the stuck bottom part of the cylinder.
4. The top part of the cylinder can be removed from the seat with a pipe wrench. Tapping it to cause vibrations and so loosen the cylinder top and work in the WD40 before trying to remove it with the wrench helped. 5. The stuck bottom of the old gas lift can be removed by pounding with a mallet on its bottom (pound toward where the seat used to be). It is much easier to remove than when the cylinder is intact. P.S. If you bought your chair before August 2009 and have not replaced the two bolts securing the seatback with the stronger ones provided under this recall http://www.cpsc.gov/en/Recalls/2010/Raynor-Marketing-Recalls-Quantum-Office-Chairs-Due-to-Fall-Hazard-Sold-Exclusively-at-Office-Depot-Stores/ I strongly recommend doing so. My son's chair broke when he leaned back on it and there are numerous reports of falls and near-injuries on the chair's Office Depot review pages.User ReviewedHow to Fix a Sinking Desk Chair Two Methods:Using a Hose ClampUsing PVC PipeCommunity Q&A
Office chairs use a pneumatic cylinder that controls the height of the chair through pressurized air. The cylinder on most chairs fails within a few years, typically because the seals are too damaged to maintain pressure. You can buy a replacement cylinder to restore full function to your chair, but this is nearly as expensive as buying a replacement. Try these simple DIY methods instead to fix your chair at one convenient height. Slide the plastic skirt off the cylinder. Most office chairs have a plastic tube over the extendable cylinder. Slide this all the way down or up, until you can see the metal cylinder underneath. Set the chair to the preferred height. You will not be able to adjust the height after this repair, so make sure you have it right. The seat of the chair should be level with your knees when you are standing. If the chair won't stay up even when no one is on it, lay it on its side. If the plastic skirt covers the cylinder at this height, you will need to remove the skirt first.
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. Slide the wheels back on. Wrap a hose clamp around the cylinder. Get a ¾" (2 cm) hose clamp (Jubilee Clip) from a hardware store.[2] Loosen the screw on the hose clamp (Jubilee Clip) and pull out the belt end. Wrap the clamp around the metal cylinder, but do not tighten it yet. Improve the grip of the clamp (recommended). The clamp will need to be very tight to hold the chair up. Give the clamp a better surface to grip by wrapping a strip of rubber or a couple layers of duct tape around the cylinder.[3] Do this at the highest visible point on the cylinder, Alternatively, scuff up this area of the cylinder with sandpaper. If the cylinder looks dirty or greasy, clean this off first. Tighten the clamp as far as possible.The chair should now be unable to slide down past the clamp. The built-in height adjustment will still not work properly.
If the chair is at the wrong height, move the clamp higher or lower on the cylinder. If the clamp slides off, fasten it over a strip of rubber to improve the grip, or try the PVC pipe method below. Measure your chair's cylinder. Pull down the plastic skirt cover the extendable, metal cylinder. Estimate the diameter of the cylinder by holding a ruler across it horizontally. Also measure the length of the cylinder when the chair is at the perfect height. You shouldn't need an exact measurement, but you can calculating the diameter from the circumference if you prefer to be precise. Buy a length of PVC pipe. This pipe will fit over the pneumatic cylinder of the chair. It should be about the same size as the cylinder diameter, or slightly larger. Pipe 1.5 inches (3.8 cm) in diameter works well for most models.[5] Buy enough straight pipe to extend from the wheel base of your chair to the seat, when the chair is at the preferred height. The pipe does not have to be in one piece.
It may be easier to work with in smaller pieces, although you can easily cut it yourself at home. One user reports using a tall stack of plastic shower rings instead of PVC pipe. These are even cheaper and easier to install, but they may not be sturdy enough to support your weight. Try at your own risk. Saw through the PVC pipe lengthwise. Secure the pipe in a vise. Use a hacksaw or back saw to cut through the pipe from tip to tip, but only on one side. The end result should be a pipe with a slit in it, not two half-pipes. Wearing a mask or respirator is recommended while cutting PVC to avoid inhaling irritating particles. If you do not have a vise or cutting tools, just leave the pipe intact and remove the chair's wheels so you can slide on the pipe. In most cases, you can remove the wheel base by pressing a retaining clip on the underside with a screwdriver. Snap the pipe onto the chair cylinder. Pull the chair's plastic skirt up or down to reveal the metal cylinder.