Remove the wheel from the garden cart. There are different methods of attaching wheels to carts so follow removal directions provided by the cart’s manufacturer.
Lay the wheel on top of a 5-gallon bucket.
Insert a long screwdriver into the axle hole, or hub, and rest the flat edge against the top of the bottom bearing, which is facing into the bucket.
Tap the end of the screwdriver with a hammer until the bearing pops out into the bucket.
Turn the wheel over and remove the other bearing the same way.
Lay a new bearing inside the axle hole. Place a small block of wood on top of the new bearing. Tap on the wood to push the bearing into position.
Turn the wheel over. Insert the second bearing into the hub and tap it into place.