Most people run their sensitivity too high. I usually run mine around the 11 o'clock position. This will hold maxium depth while not having the machine false to much.
Every maching might be a little different. Even thought an air test is not an accurate way to guage depth for the Sov. Turn your sensitivity up all the way air test a quarter, when you first notice the first loss of depth stop and turn the knob back slighty. This will let you run at full depth, and stop most falsing, it will help make some of those old iron signals not as hot.
HH
