Determine what pitch you would like to sound when you hit the chimes. The main chimes in front move diatonically from middle C to the F approximately an octave and a fifth higher. The chimes in back are chromatic, starting with C-sharp and D-sharp on the paired set and F-sharp, G-sharp and A-sharp on the triple set.
Using a hammer, hit the new pitch you would like to play, by hammering against the rim of the tubular chimes.
Create a louder or softer sound, by changing the degree at which you hammer against the chimes. You can also place a cloth tied around the center of the chimes, to muffle the level of sound produced.
Change the pitch of an individual chime, by ordering a replacement chime that plays the specific pitch you want. Remove the screw that holds the old chime in place. Then replace it with the new chime.