Hello, I'm trying to fix an old 6 & 12v battery charger. I'm pretty sure the bridge rectifier is bad. It's an old mallory one, probably about 2" square plates with a 3/8 bolt through the middle. Can I replace it with a newer type? What rating? I have a 19v secondary xfmr voltage applied to the rectifier. Primary is fused at 2A. Max charge current is 20A at 6V.