Left shoulder drops which is common with wide stances. Playing the ball too far forward. Sequence of transferring weight is off/late. Swing plane might be too steep or too flat.

This has always been the toughest thing for me to cure. As I tire or relax, the left shoulder and hands will drop or I get stuck trying to transfer weight from back to front foot. Flattening out my swing plane has helped. Narrowing my stance and focusing on keeping my shoulders level have helped. It is a constant battle though. I agree that video would explain a lot.