I have had two detent springs break. The first time the bike was stuck in 1st gear, but I was less than a mile from home so no problem. The second time it would change gears okay, but would jump out of 3rd and 4th, unless I held pressure on the gear selector. I rode it from the west coast back to Baltimore like that.
I believe that there was another chap who ended up stuck in 5th gear, and rode it half way across America in 5th gear to get home.
It is a reasonably easy repair, if you have appropriate tools. It is even easier when done under warranty.