There is a good chance you don't have a problem with squelch at all, but you do have a problem with interference from all the other electrical devices in your panel. Your radio is doing exactly what it is designed to do.........present a weak signal for you to hear! If you turn down the internal squelch, you will also be denying any and all weak signals that everybody else is hearing. What other instruments do you have in your panel and how close are they to your radio? Try turning off the other instruments,one at a time to see if your radio stops breaking squelch.
JJ