A caster is another name for each wheel that you find on the legs of rolling office chairs and tables. If one of the casters goes bad and doesn't roll smoothly, you can simply replace it. Find a new caster that fits at your local hardware store. The removal instructions vary depending on the manufacturer, but overall it is a quick process.
Place the chair or table on its side or upside down.
Grab the caster, and attempt to pull it right out. Some casters aren't nailed or attached to the chair leg but are held in place by the weight of the chair.
Loosen the caster with a screwdriver if it is attached to the bottom of the furniture with screws. The screws are usually located on the side of the bottom leg of the chair or table.
Pull the casters out with wire cutters if they're lodged deep into the bottom leg of the chair or table. Turn the furniture upside down, grasp the caster leg tightly with the tool and pull it up and out. If it still won't come out, proceed to step 5.
Set the lifting end of a pry bar underneath the base of the caster, while the furniture is still upside down, and gently push the handle down until the caster comes out.
Be careful not to damage or scrape the edges of the furniture when you're removing the caster with tools. If possible, wrap the leg and surface of the chair or table with a thick towel to protect it from damage.