Just like the brakes on your car, the brakes on your Sequoia wear out. Before you go ahead and order replacement casters, try adjusting them.
* Only the new double caster is adjustable
First turn the brakes off using the foot pedal. Underndeat the caster is two adjustment nuts, the one for the brakes is the one in the center (see Diagram 1).
Using a half-inch socket or wrench, turn the adjustment nut clockwise to tighten the nut thus tightening the brakes. Usually only a few turns are required to tighten the brakes.
Do the same for the other caster and you just saved yourself the time, money and headache of replacing the casters!