I have had a similar, yet intermittent, situation for the last few months. Electrically, everything tests out good, but sometimes when I hit the starter i get a clicking or light buzzing from the junction box. Lots of research on years old posts seems to indicate that it is probably the starter relay inside the junction box. This seems to be a semi-common failure and is a relay that is not easily replaced unless you have electronics/circuit board skills. New junction boxes go for about $120 on Revzilla, or I am sure a used one can be sourced through the normal channels. My solution has just been to ride it until I want to spend the money. The bike is light so it is easy to push and pop the clutch to start so I just do that if it doesn't fire over...