Welcome to the club Jim I've also been struggling with a cupped left wrist at the top... Here are some of my previous posts which all have some mention of the left wrist...

http://www.golf-tuition-online.com/v...ead.php?t=3507

http://www.golf-tuition-online.com/v...ead.php?t=4369 (Please check my swing plane)

Let me know if you find a solution!