Not very proud of it but was in a hurry yesterday morning, needed to move a garden tractor with a weak batt. and hooked it up wrong, been hooking up chargers for over 50 years. Circuit breaker tripped followed by a wisp of smoke. Both button diodes are junk, one was covered with little solder flakes or something. I've got a big charger but I like this one better, had it since 1977. The diodes are hard to read but looks like AR 004 and one had the arrow toward the plate in the back, dropped the other one but think it was in the same direction. Are the little diodes the kind of thing Radio Shack would have or where would you look?