Lay the chair on its side on a flat surface.
Remove the casters from the base of the chair. Place the pry end of the pry bar or hammer between the metal ring just above the caster wheel hood and the bottom of the caster socket and pry the caster out. This will depress a small ring at the top of the caster stem and allow the caster to pop out. Repeat with each of the casters.
Install the glide by placing the stem into the caster socket and firmly pressing it in until it clicks into place. You may need to tap the glide a couple of times with the hammer or the back of the pry bar before it clicks into place. Repeat with each of the glides.
Set the chair back upright, making sure that the glides do no drop out of the caster sockets. If any do, repeat Step 3 to ensure proper seating.