The pin was meant to keep the wheel out away from the body. After it fell out, the wheel migrated close to the body, making it necessary to move the wheel back out about 9" or 10". I jacked up the center, loosened then removed the cogs but could not move that wheel. I ended up having to remove the wheel to move the hub into position to install the pin. For me, I found the hub was heavily worn so I replaced it. If it had been OK, it would have meant reinstalled the cogs, torquing the bolt and pushing the pin into place. After putting the clip on, I put on some wire around the tip to make it harder for the clip to get removed and the pin fall out.