With considerable effort, I found a PDF of the service manual with electrical schematic online. The manual contains a complete test procedure as well as coil winding resistance specs, disassembly instructions, etc. With that, I proceeded to take the end cover off the machine and check the electrical components. In the photo below one can see the rotor, stator coils and some of the wiring.
A Quick Word About Generators In General
I tested the rotor coils, stator coils, rectifier and filter capacitor with a Klein brand Model MM200 multimeter purchased from a big box home improvement store for $49. All components except for the capacitor tested within acceptable range.
A new capacitor is on order - we'll see what happens when I get it installed.