There are four spare parts. One is a pivoting side panel, another is a plastic wheel bearing, the third is a grating or base with several associated screws, and the fourth is the face of a push button with an arrow sign.
Dimensions
Base: 2 in x 2 1/2 in x 1/2 in; Bearing: 1 1/4 in x 1 1/4 in x 3/4 in; Corner panel: 1/2 in x 7 in x 1 1/4 in