Hard Hammers

[Phil Bondi]

It depends what kind of hammers you're talking about. If 
they're on an Asian rim piano, try this:

Alcohol/water..soak them good up to #60. 61-88 less soaked.
While they're wet, Vice grip them.
test.
Steam if needed.
spot-needle as needed

I've performed this method on a number of hard hammers from 
Asian pianos with good lasting results.

-Phil Bondi(Fl)