Not really a big deal, but if it happened to me it'll probably happen to you...
There is a light gauge metal bar behind the seat. The tool box is mounted on it.
I noticed it was loose. The left side nut had come loose and fallen off. The right side nut was loose but still there. Replaced the missing nut and tightened the other and all is well again.
It's hard to get to and much easier if you take the bolt off that holds the tail light to the fender and slide the tail light out.
There is a light gauge metal bar behind the seat. The tool box is mounted on it.
I noticed it was loose. The left side nut had come loose and fallen off. The right side nut was loose but still there. Replaced the missing nut and tightened the other and all is well again.
It's hard to get to and much easier if you take the bolt off that holds the tail light to the fender and slide the tail light out.