Bad picture, apologies. There's no trouble shooting this. I'm not here to argue but I've had several of these and only ONE that ran on the stock charging system. Sure it's how owners treat them and modify. Heat from different pipe setups can melt insulation off of stator windings. Sitting outside or bad barn storage. Go with a PMA. You have more wiring experience than I do! I did recently make a stupid mistake. Make SURE to have the right reg/rec for the PMA. I bought one off of Sparck Moto for $45 that was right. Even with this try to have an old standard battery hooked up to check voltage is 14 or under..
Because it's yet another PMA thread. One of like a thousand on here.
Search button, use it.
People are always bashing on a tried and true charging system and immediately want to replace it with a PMA. Learn to troubleshoot, learn the bike.
Look at the PO's wiring. There could be one loose wire on there and he just spent a ton of money.