I would start with checking the battery voltage when running. See if it varies with RPM.
As for wiring, check the main grounding points for the battery (back of battery tray) as well as those in front of the oil tank. The back of battery tray grounding via a recessed head screw is a really poor decision on the part of MMC, IMHO. They really should have provided a welded to chassis stud for this purpose. One should probably remove the screw and clean the contact points annually to prevent issues.
