I have a 1949 model D i picked up from Canada a while back. It runs and drives and is a helluva head turner especially from where I am located, but there is an issue about it. The previous owner has what i believed "rewired" the entire tractor to be a Positive ground tractor and to start it (electric start obviously) i have to take the negative cable and bash it onto the negative terminal. What are the procedures necessary to bring all that back to original so I don't have to keep running out to get a new battery every other summer? All help would be appreciated!