Hi Stuart,
I'm not sure if you fixed that wheel, it looks like you are missing the nut that the bolt would screw into inside the wheel housing. It should be on the inside compartment.
[image|2698033]
. To access the compartment, unzip your bag through the main compartment, then unzip the inside liner to access the inside handle and wheel compartment.
I have attached an image that I hope helps. The nut that came off could still be inside your bag. Otherwise take your bolt to a hardware store and find a replacement nut.