[Alan Anderson]

That code continuously increments a value whenever the Gear Tooth Sensor is high. It won't work because it doesn't count the number of times the signal from the Gear Tooth Sensor goes high.

If the signal is slow enough, you can poll it and count low-to-high transitions. Just remember the previous state of the pin, and if it was a zero last time but is a one this time, increment the counter. However, if the signal changes so quickly that you can't guarantee you'll be reading it often enough, you'll need to use the hardware interrupt feature of the RC's first few digital input pins.