Additional items you may wish to check - see Monte's post on lock trac. [www.ahrps.org]

Seems you 'may' be experiencing an issue w/ GB. If not the coil, then you might be facing an issue where the ground balance is being left in a locked position and the ground you are on is changing such that you are overloading. Additionally, the toggle switches can go bad, and you might possibly have a switch that is 'sticky' after you ground balance or pinpoint.

I had my tones fail on my M6 recently, and took the display apart and found the connector had separated, no longer allowing for proper tone ID.

Send an email or give a call to Whites Service in Lebanon, OR and the owner may have some advise for what you are seeing.

I'm having background color failures on one of my V3is, and no doubt some of the logic in the graphics processor has gone bad. Probably a board replacement for me.

Best of luck Jim,
Zincoln