First, definitely make sure to use the same grip on snatch balances that you use for snatches. If your snatch balances are significantly heavier than your snatches, it may be that the SB isn't different or wrong, but that it's all wrong and the heavier weights of the SB just make it more obvious.
Do you hold your hook grip in the overhead position? If so, I would suggest learning to release it. I believe that most people can get a much sounder hand/wrist position without the hook. Also be sure that the bar is in the palm just slightly behind the middle of the forearm, not farther back. The hand/wrist needs to be relaxed and settled in - make sure you're not trying to hold your wrist in a neutral position.
I would suggest playing with the position with snatch presses or push presses to find what is comfortable and strong.