New parameters (Down Force, Up Force, Balance Force, and Average Friction) are defined for evaluating important “stroke characteristics” of individual key actions of one or more pianos or keyboards, describing exactly how these parameters are to be tested, measured and determined. The new parameters are designed to replace the prior art parameters of Down Weight, Up Weight, Balance Weight and Friction. Various methods, means and apparatus are disclosed for accurately testing, measuring and determining these new parameters, with the capability of performing thousands of measurements—on thousands of different key mechanisms—in a short amount of time.