That's the problem we cannot even get to the scan page to scan for air channels. It says it's not available, which to me means we are not getting signal from air antenna even though we have pushed the antenna button on dist. panel. On our 20 year old GBM you are correct the booster switch is hidden on side of TV under dash. This TV is huge and above the cab. We have even had our own guru searching for it (an engineer w/Valpo degree) he fixes all our problems for us this one even has him stumped. Thanks for your input we will keep checking and try calling Thor.