Chronograph Stuck

I have a Tag Heuer Calibre 16 chronograph watch. I learned from this site that it's a 7750 movement. The chronograph main hand is stuck at 30 and the buttons won't stop or reset it. I can see the buttons pressing from the open caseback but they are just moving the levers and not clicking anything or resetting it. Is this anything someone had experience with before? Service for 7750 costs a lot and I wonder if I can fix it myself. Thx