Well, installing a new hammer cured the push off problem on my new-to-me M17. Fortunately S&W still had old style (pre MIM) hammers for this model. I actually ordered both a hammer and a trigger, but before I received them I determined that the hammer was the problem (which I did by swapping out parts from some other K frames I had.)
This is good, because I was able to get a hammer that matched the original one. With the trigger I had to get a MIM, and it was smooth, not serrated. I'm not saying I'm anti MIM, but since the gun originally had the old forged parts I wanted to keep it that way if possible.
I think I'll return the new trigger to S&W. I don't need it, and since its new style I can always get one if I ever need one.