if the lock pin is falling in to place that's ultra dangerous...
you may think you'll not use full lock or you'll just be going slow and can stop. No 100% you'll fall on the floor (probably in a nasty manner as will go the opposite way you want, so will surprise you).
Different bike, but it happened the same way to my brother. Either something is detached (broken) or a spring holding it up broke. Either way sounds nasty it seems to have failed dangerous. Please left us know what you find
He did. Post # 17
