Lay the chair on its side with the arm to be repaired facing up.
Remove the 1/4-inch bolts or screws from under the top of the arm to pull off the arm pad.
Insert one of the 1/4-inch bolts or screws through one of holes in the chair's arm and position the new arm pad so that the screw or bolt fits into the proper mounting hole of the pad. Turn the fastener so it engages the pad. Do not tighten it at this point.
Insert the other screw or bolt through the second hole in the arm rest and into the mounting hole of the pad. Turn it to engage the fastener in the mounting hole.
Tighten both bolts or screws.
Remove the two bolts or screws that attach the chair arm to the underside of the seat and take off the old arm.
Position the new chair arm so that the holes at the bottom line up with the mounting holes in the base of the chair.
Insert one of the screws or bolts through one of the holes in the chair arm and into the mounting hole in the underside of the seat. Turns it to engage the fastener in the hole. Repeat with the other screw or bolt.
Tighten both fasteners.