All the tuning forks need to be coated with WD-40 at least 3 times a year to prevent rusting.  To remove rust make a .1 Molar solution of Ammonium Citrate and let the metal parts soak in this for several hours.  rinse with vigorous scrubbing under running water, dry, and oil immediately.  DO NOT scrape or rub the forks with any abrassive materials as this will change the pitch and vibration of the fork.  Broken boxes need to be reglued with special glues to preserve their resonance properties.  

Hook the microphone into the pre-amp and the pre-amp into the oscilloscope. Set the microphone into the resonance box of the tuning fork. When the tuning fork mounted on the box is struck the sinusoidal properties of the waveform are shown on the oscilloscope.  The tuning forks without the box will not display pure sinusoidal waves.