Install a 3/8 Flat Washer onto one of the 3/8 x 2 Bolts.

Place an axle spacer onto the 3/8 x 2 Bolt.

Place the wheel onto the axle spacer. Note the position of the extended end of the wheel hub.

Place the axle bolt through the single hole in the short end of one leg. Thread on and tighten a nut. Make sure the wheel spins freely on the axle assembly. If it doesn't disassemble and check for burrs in the wheel axle bore and on the axle spacer. Remove any burrs found and reassemble.