Somewhat off topic: Allen Series 12 Organ

[holmesuser01]

I have a large Allen organ that followed me home in the fall of 2009. It had one helluva hum in the audio output amplifier, so I recapped it, all except 2 bumblebee caps, and a tiny electrolytic between the first and second audio stage. It has performed well until now.

I've got some distortion that I *think* seem to be getting from the low tones off the tone generator. It's power supply is filled with electrolytics, but seems to work properly.

The audio comes from the generator, thru a tone control network of capacitors and resistors. All caps have been replaced here, and the resistors checked. Then, it goes to the amplifier.

Im looking at sine waves on my scope, and I can see definite distortion.

The Allen Organ Company kindly sent me a PDF of the organ systems, and voltages on B+ are about 35 volts low. It has a large selenium rectifier that supplies power to the relay networks, and it checks out OK.

I am concerned with the type 83 rectifier. I replaced the original, which would glow bright blue when a chord was played on the keyboard. The replacement, also marked as an 83, shows nothing when chords are played.
I know this rectifier has mercury vapor, and requires some warm-up time. The system has a 15 second time-delay on B+ to the tone generator.

The electrolytics on the power supply chassis are cool to the touch, and are not leaking. There is no hum anywhere.

Does anyone on this forum know how to troubleshoot this creature? Should I start replacing the electrolytics in the generator supply? Like I said, the B+ is constant throughout the generator, but a bit low. All tones are correct, except for a couple, and I am substituting capacitors to bring them back to life. When it arrived here, about half of the keys didnt sound correctly.

I am posting this here because there is no real place at Audiokarma for this.

Here's some images of what I'm dealing with here. Also, the rectifier on the main power supply in the pics is an 84. It's all I had at the time. The 83 is in there now. The tone is still distorted using the 84, also.

Thanks for looking!!