Action regulation is the piano technician's term for adjusting the approximately 8,000 parts that make up the piano's action mechanism so that the piano plays properly. The action of a piano consists of the keys, hammers, and other levers and springs that move the hammers to the strings when the keys are played.
Regulating the action requires skill and judgment, and when properly executed, it can transform the piano's performance capability. Some common symptoms of a piano action that needs regulation are:
--The piano is difficult to control in softer playing
--Repeated notes are difficult to play, for example in trills and other ornaments.
--The dynamic range seems smaller than it should be, for instance, it's difficult to play softly but the instrument seems to lack real power in louder playing.
--The touch feels uneven.
The cost of regulating the action can vary, depending on how old the piano is, what kind of condition the hammers and other parts are in, etc. Severely worn action components and hammers may require that the action mechanism go into the shop for reconditioning or even replacement of parts. But many pianos can be regulated right in your home in about a half to a full day.