The damage discussed here would happen only in an extreme situation where someone pushed in the wheel of a and then quickly released it to cause a loud click. This can break the plastic that holds the axle in position. We have found that, in these cases, it is possible to repair the cart by clamping the axle down and out of the way and the using epoxy cement to glue the pin in position as shown in the photo attached.
Note that the axle mounting is different on the Vernier Sensor Carts Go Direct® Sensor Cart (Green), order code GDX-CART-G, $169 and Go Direct® Sensor Cart (Yellow), order code GDX-CART-Y, $169 and Encoder Carts Motion Encoder Cart, order code DTS-CART-MEC, $159. This note does not apply to them.