His "ifs" are in lower case, HrL
His "name" is ROAR.
I would have also added in upper case: CHECK THE GAUGE OF THE BATTERY LEADS AND THE FRAME TO ENGINE GROUND STRAP. It was quite common to simply replace those cables/straps with whatever was available. 4 gauge or smaller size 12v cables/straps are too small for 6v systems. Use 2 gauge or larger size (smaller gauge number) cables/straps. I over-do it with 00 gauge cables.
Keep asking questions Aaron (and, keep posting your progress/questions/problems).