Sounds like this was the nav/com fuse! You might not have noticed that the radio went dead too? If disturbing the fuse makes that kind of difference, it is obvious the problem is in the fuse itself (automotive fuse, intermittent open), the fuse holder (weak or broken spring, corrosion) or in the connections to the fuseholder. Gotta be in that general area! If it were anything else, playing with the fuse for a month wouldn't make any difference.
