Hi Darney,
A few suggestions:
Inspect and clean the engine to machine electrical harness connector.
Lift the control panel, unplug the connector and the yellow wire from the keyswitch. Check continuity between the terminal for the yellow wire and the battery terminal with the keyswitch in the on position. There should be good continuity in the on position and an open circuit with the keyswitch in to off position.
Check the machine electrical harness grounds which are connected to one of the engine mounting bolts.
The basics of this type of charging system are:
The stator puts out AC, half of which is the wrong polarity.
The regulator/rectifier blocks the wrong polarity part of the AC.
The correct polarity part of the AC now is pulsating DC and regulated by internal components of the regulator/rectifier and sent out thru a single positive wire thru the engine harness to the machine harness, thru the fuse in the yellow wire and then to the keyswitch.
When the engine is running, the charging system output flows thru the keyswitch to the battery positive, back thru the fuse in the red wire which is connected to the battery terminal on the starter solenoid and back to the battery for charging.
This type of charging system needs to be electrically isolated when the engine is not running as battery power will backfeed thru the regulator/rectifier and into the stator which will drain the battery fairly quickly. This is done by the keyswitch when in the off position.
Any interruption the charging system output to the battery while the engine is running can cause the regulator/rectifier to fail.
Trouble shooting the charging system should be done with a fully charged battery.
All this said, my spin on your problem is that you may need a new regulator/rectifier, but you need to check the rest of the electrical system to make sure that there are no other problems with continuity.
I have had to add a ground bonding wire to some regulator/rectifiers as the plate that they are usually mounted on can sometimes have a grounding problem where it makes contact to the engine, the R/R base needs to have a good ground.
Have fun!!!
Mad Mackie in CT:laughing::biggrin::smile: