Casters can bend or break due to uneven weight distribution, manufacturing flaws, or general wear-and-tear. If your chair is on a very uneven floor, the casters won’t all touch when you’re not sitting in the chair, and you’ll lean to the “low” side of the floor while sitting. You can’t really blame the chair for that!
Alternatively, wait until you pull off all the old casters, then take one with you to an office supply store and use it to find a matching replacement set. Pay particular attention to matching the shape and size of the caster stems, which insert into sockets at the bottom of the chair. If all the casters are in good shape, and the chair is on a level floor, skip ahead to checking the second most likely cause of a leaning chair—the seat plate.
If you can’t pull a caster free with your hands, wedge the blade of a flat-head screwdriver into the small gap at the meeting point of the caster and the chair. Use the blade as a lever by slowly working it back and forth. Once you’ve worked about 1 cm (0. 39 in) of the caster stem out of the chair socket, pull on the caster wheel again. In rare cases, the casters are secured to the bottom of the chair with screws. If you see screw heads where the caster connects to the chair, use a screwdriver to loosen the screws and take off the caster. [4] X Research source
Casters usually pull out of the sockets more easily than they go into them. Lubricating the sockets makes the process easier. If you don’t have a lubricating spray, rub a pea-sized amount of petroleum jelly (e. g. , Vaseline) onto the stem of each caster instead.
If the caster’s design provides you with room to tap near the base of the stem rather than at the bottom of the wheel, do so. This reduces your chances of deforming or breaking your new caster!
Find a matching screw by rummaging through your junk drawer or, better yet, by taking one of the existing screws to a hardware store. Flip the chair upright and sit on it after tightening or replacing any screws. If it still leans, keep searching!
At this point, you may decide that it’s preferable to just buy a new office chair. However, if it’s an expensive chair, it’s likely more cost-effective to remove and replace the seat plate.
Smacking the seat plate with the mallet may dent it, which isn’t a problem in this case since you’re replacing the plate. If, however, you’re disassembling the chair and plan to use the same seat plate, strike the underside of the chair right next to the plate instead.
Seat plates are not universal, so a generic replacement is unlikely to fit or function correctly.
If you’re having trouble popping the column’s stem into place, apply a small amount of spray lubricant (such as WD-40) into the socket, or rub a pea-sized amount of petroleum jelly (like Vaseline) onto the stem. You can now test out the chair. If it no longer leans to the side, congratulations! If, however, you’ve replaced the casters and the seat plate and the chair still leans, strongly consider investing in a new office chair.
