Hi Jon,
Having done more research on 4016 models, your Vanguard is a 303447 model with a basic charging system.
There is a two conductor plug on the reg/rect that connects to the stator output. Disconnect this plug and connect the leads from your multimeter to the stator output, put the multimeter in the AC Volts in a range higher than 30 VAC.
Run the engine at WOT (3,600 RPM) and if the voltage reading is 26 VAC or higher then the stator is OK.
Shut the engine off, disconnect the battery positive, disconnect the plug from the rear of the keyswitch and inspect and clean the contacts in the plug. You can remove them one at a time and clean the contacting surfaces with a small wire brush. If you find that the plastic plug has melted and causing problems with the contacts then you need to correct this problem by replacing the plastic connector or replacing each connector with a spade slipon connector.
The melting of the plastic plug is cause by heat from a connector that has corrosion which causes a high resistance connection.
There is a 3rd wire coming from the reg/rect and it is the DC output to the battery and it has a plug on it, check it for corrosion and security.
When you have done all this, reconnect the battery positive, reconnect the stator/reg/rect plug and run the engine with a multimeter across the battery in DCV position and check the high RPM voltage.
If the voltage rises to 13.5 or higher then your system is OK, if not then you will need to replace the reg/rect and recheck the system.
Meanwhile, charge the tractor battery as troubleshooting charging system problems is much easier done with a fully charged servicable battery.
As these tractors get older all plug connections are suspects for corrosion and all should be disconnected and cleaned and reconnected.
Bob MacGregor in CT :mrgreen:

:winterrules: