Turn the chair over so the legs are upright and the seat is toward the floor.
Compare the wheel of each leg to see if one of them is bent or otherwise defective, which would cause the chair to tilt right or left. If one of the wheels is damaged, it will need to be taken off and replaced. Most wheels can either be pulled off or can be untightened with a Phillips or flat-head screwdriver.
Inspect the legs of the chair to see if a screw has popped out. If so, try to locate the screw in the surrounding area. If the screw cannot be located, and you do not have a similar size replacement screw, you can purchase one from the local hardware store. However, be sure to take one of the remaining screws with you to ensure that you get the correct size.
Examine the black plate on the bottom of the chair’s seat. This plate contains several screws and bolts, as well as the adjustment lever and hydraulic lift. Check to see if any screws or bolts are loose. If so, tighten with the appropriate type of screwdriver -- flat head or Phillips -- or with a wrench. However, if any bolts or screws are missing, they will need to be replaced following the replacement steps outlined in the step above.
Inspect the black plate for damage. If any part appears defective, the entire plate will need to be replaced. If you have the make and model number of the office chair, you should be able to order a replacement plate either online or from your local office supply store. All of the screws and bolts will need to be taken out of the black plate to remove and replace it.
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