had it happen to me on my monster 900. looks like the top small spring on the gear selector barrel as stated. It is on the latch key bit of the assy. If you do end up doing it, be sure to get the big spring as well.!! I went to two specialists for advise and they both said it would be the small spring. When i stripped it, i found that both had snapped. It takes 5 mins more, but worth the piece of mind.
You're all wrong! It's from the selector drum detent arm and is located behind the driven primary drive gear at the back of the clutch. The clutch and RH cover has to come off to replace it.
The gear selector barrel return spring, which broke on my MTS1000 looked similar. Couldn't change gears after that. Part cost £8, takes 2-3h to change it in your own garage.
