If 2ga worked in the beginning then it is OK now. With electrical issues a person wants to start with the batt. any possibility you can sub in a known good one to elim that? Then start cleaning ALL connections including the ground path. Might be an internal starter issue but more likely connections/terminals having borderline continuity. A longer shot would be if the eng friction has increased (I ain't thinking that). I would tho ground the coil secondary wire when it does it to take eng compression out of the picture (it'd take 1 minute). Holler back when you can with any news.