Is it possible to change servo pins to correct this?
Of course. That's why I mentioned it.
Not entirely sure what you are referring to here..
Upon re-reading your code, I was wrong. I missed the bit where you actually read the ping sensor, and say the part where you are reading the potentiometer, and thought that that was trying to read something from the ping sensor. Sorry about that.
The ping sensor does nothing with PWM. The Servo library doesn't either. However, the Servo library does use timers, which interferes with the ability to use PWM on certain pins, depending on which pins the servos are connected to. I'd try, if possible, to not use PWM pins for the ping sensor. The analog pins can be used as digital pins, if you are low on/out of digital-only pins.