I purchased a original 200A power cord (flat oval at the keyboard, non-standard design) on eBay and brought that to KWARTZLAB tonight to see if we could get the old machine to fire up.
Eureka! The power/volume pot seems to be a little dirty, but after a few tweaks of the knob, the power light came on and I heard amplification!
End result, the amplifier circuit and vibrato circuit are working just fine. All the keys will need to be loosened up, cleaned, etc. But all notes appear to be working (although a few sounds not so healthy), and the sound from the speakers is oh so sweet.
Now to buy baggies from the dollar store to put the various screws, nuts and small parts in when I begin to take the machine apart over the winter.
Next step, purchase hammer action repair kit and some other parts and start dismantling the keyboard down to the base plate.