One minute a week fast, roughly? It's not something I personally would fret about.... However, best of luck in fixing it.
There used to be a Yaesu FRG-7 eGroup on Yahoo. Whether it's still there is a good question. Either way, it used to be active as late as 2-3 years ago, and I'm guessing that if there was an FRG-7 group there probably was also an FRG-100 group, as a lot of those radios were sold over the years.