I've now got it "sorta" working. I switched over to the lower frequency PWM pins (10 and 11), removed the integral (caused WILD oscillations) and I have been trying to follow along with various tutorials on PID tuning and it still oscillates. I've got it oscillating less... but still crazy amounts.

The problem, I think is that the potentiometer changes value very quickly. I am dealing with a very small range of motion here. Just kicking the motor a little can way overshoot. I am so close to giving up on PD control (remember, I zeroed the Integral).

Raising the integral even to 1 caused the motor to go absolutely nuts. A P of 2 and a D of 1 seems to be working the best.

This is what I think I understand:

P = How much force to move towards zero position

D = Pre-act (predicting what the output will be over time)

I am just not positive that this is right for me. What I am getting out of right now is no different than my simple If currpos > pos, then move left etc... routine I was using. In fact, even that actually got it right ocassionally!