Casters are considered a normal wear and tear item and unless there are extenuating circumstances, are generally not covered under the warranty. A set of two may be purchased for around $16.65, including shipping. Use only Cosco casters on Cosco products, as these are the appropriate size for leveling in hand truck mode when all wheels are in use; any variation from this would void the warranty.
Note: We only offer replacement casters for Cosco hand trucks that do not include an assisted mode. If you are uncertain about whether your hand truck has this feature, load-assist offers support when the cart is tilted from an upright position.
For units without the assisted mode, the casters can be replaced using part S45005509, which has a 4-inch diameter wheel. Each caster is comprised of a wheel, wheel housing, ball bearings swivel, and bolts with locknuts: