Left thumbstick is glitched/broken

i have the same issue i called support it is something internal. now i dont recommend to take the controller apart. but if its under warranty it is free if not you'll have to pay on top of that you'll probably have to pay shipping as well to get a replacement.
the replacement will be a day one controller. it will take about 10 days for the replacement to come at your door. Now if your like me then you might wanna buy a new controller if the shipping is too overprice or you dont want to wait.

hope you find this helpful

I have the same problem only it started AFTER I replaced the left thumbstick. Now the click is intermittent. It only happens in Halo games where left click is sprint. Rarely when you click it will STAY sprinting. Most of the time you have to HOLD DOWN the
stick to stay sprinting. Sometimes it won't work at all. This all happens during the same game play. I replaced the left thumbstick because it was old and wouldn't return all the way to center. Now the left click won't work properly. I've tried 3 different
brand new stick components from 2 different suppliers and the same thing still happens. All the new sticks check out on the multimeter. Does anybody have any clue?

Your comments aren't very helpful. I was hoping someone with controller repair or electronics experience could help.

^^ In conclusion, spend all your money to fix it rather than learning to play on a different button layout.

"Buy new Xbox, not refurbished, new controller(not an off brand) and a new halo cd+Gamertag. I guarantee it will fix. "

Gash, when u ask for help with something, i'll make sure i give you a smart @@@ answer. I swear some people are just punk a**es no matter what....

re-install halo4 disk 1-2, use a CORDED controller? turn off crouch toggle, wish i had better advice. but i didnt see any of these up there.