Raise the corner post of the bed frame which has the defective caster wheel. A helper can lift the corner while you work.
Remove the old caster by tapping on the top of its steel frame with a hammer and a drift punch. The caster will have either a ball-shaped tip at the end of its pin or a compression ring surrounding the pin shank that is snapped into place inside the bed frame post sleeve.
Apply a thin coating of petroleum jelly around the ball-shaped tip of the new caster wheel pin for lubrication. If a compression ring is installed on the pin shank, place the jelly around the ring.
Insert the new caster wheel pin into the steel sleeve of the bed post until it snaps into place.