Set the hammer blow to 1-3/4" by having the shanks resting on the rail.
Shim the rail with firm (non-compressible) felt glued to either the
rail or action bracket.

The capstans are adjusted to minimize lost motion, just enough to let
the jack slip back under the hammer butt.  Tip: when adjusting lost
motion, lightly pull back on the rail; if a hammer does not follow the
rail it is adjusted too tightly.

I usually allow 1/16" lost motion.  If it becomes very humid in the
summer, you will need more lost motion to allow for felts swelling.

The hammer rail lifter rod does not support the rail but rather is
adjusted for about 1/8" free play before contacting the rail.

If the butt felt is too hard and the jack makes too loud of a noise
upon its return (there will always be some noise), replace the felt.

If you want to really adjust the action to the Nth degree, get a gram
tensioning gage and adjust the spring strength on the jacks, dampers
and hammer return springs.  That would make for an extremely even feel.

Regards,

Jon Page,   piano technician
Harwich Port, Cape Cod, Mass.