watertown is about 2 hours in the wrong direction for me. there was a member here once from fort drum near watertown but i can't remember their username.
power comes in one side of the fuse box, goes through the ammeter and to the other side of the fuse box. if you only have power on one side of the fuse box it is probably the ammeter or the connections at it.
maybe something helpful here : Assorted Engine Analyzer Manuals from Sun, Allen, Thomas : Sun Electric Co., Thomas, Allen and other respective authors / manufacturers : Free Download, Borrow, and Streaming : Internet Archive