The Sound Level Meter wont calibrate and it looks like the piece of foil under the grid on top of the microphone is ripped. What should I do?
NEVER remove the protective grid from the top of the microphone. The thin piece of material that looks like foil is actually the diaphragm. The diaphragm vibrates when exposed to sound waves. Those vibrations are how the meter measures the sound level. If the diaphragm is damaged, then the microphone is damaged beyond repair. A replacement microphone must be purchased.