I have a "49 WD that has been a problem with the starting system. A new battery (6v) just can"t seem to turn it over. In fact, the starter switch (new) doesn"t appear to connect until I put on a 12v jumper. If I install a 12v battery would I need to change the generator set-up? Or is this inadvisable. I have a friend who uses 12 on and Oliver and gets by great.