On my Farmall M, the generator had been rebuilt and converted to 12v when I bought it. It has worked well for the last 10 years but I noticed today the gauge wasn’t moving… I assume the generator isn’t charging, as the battery was a little low on power. On 6 volt systems i know you sometimes have to jump the box to get it charging again… are 12v systems similar? If not where should I start testing things?