Dave plus one but I also know that...
...Noel knows his stuff.
My thought is...Go buy a new hand and file it until it works while keeping in mind, Dave's encouragement to consider the interaction of the parts at each reassembly.
I am assuming the new hand will be longer than necessary which means some filing is in order as is the case in most hand replacements.
The metalurgy in the hand is critical and indeed I think it is at the heart of most of the criticisms against ASM for soft internal parts.
I think you may find that not only is the length critical, the striking angle of the face can effect the smoothness of operation.
I found that in a small revolver (a five shot .36) I actually rounded the face of the hand.
My reading of history convinces me that most bad government results from too much government. Thomas Jefferson