I feel that what happens at strike is most crucial to the piano's TPR (tone, power, and repetition), and that the best result shares compromises proportionately to favor the hammer crown-to-string impact.

I employ the sharp point of a broach, inserting it in the bushing material, generally outside the assembled part, and turning it around the surface of an imaginary cone while applying pressure. I follow this with working the part to settle the spot I have just compressed. I can usually cut the swings of a grand hammer in half, if I want to, with stable results.