I recently bought my first metal gear servo off ebay... a used one. (HS-645MG or something like that)
It works, but it's not properly calibrated. I've disassembled it and verified that the center position does not place the potentiometer in a center position. Thus, it doesn't have full range in the counter-clockwise direction.
As I understand it, I have two options here: I can either modify the case slightly to let the limiting pin on the largest gear rotate that last bit, or I can do something with the potentiometer... (replace, wire in a resistor, etc...)
Is sending a different range of PWM signals a workaround?
And yes, I think I'll stick to buying new servos rather than used ones in the future