Diagnosis
The floating plate spring system is misaligned or the hinge screws are loose.
How to Fix It
Unplug and cool. Open the plates. Check the four small silver springs under the top plate. Ensure they're seated in their slots. Tighten the two hinge plate screws firmly.
If That Didn't Work
The floating plate mechanism itself is warped from a drop. This requires a full top plate assembly replacement.
Heads Up
Do not overtighten the hinge screws. It strips the plastic housing and makes the problem worse.