The moral to the story.....
If you experience battery boil-over, separate the two batteries and test them independantly. Apparently one weak battery will fool the charger into pumping a charge until the cows come home, boiling over both batteries in the process. I replaced them with two new (bigger) batteries from Walmart. So far so good. No boil-over yet.
Thanks for that info Ron, I will check the batteries separately to see if that is the reason for my boil over problem.