If you're technically competent, or have someone else who is, and can refer them to this page, it lists a few changes that you can make to the organ, if you feel the need.
Re-capping
I'm no fan of people blindly replacing all the caps on devices, often it's just not required. But I'd found that just about all power filtering caps on my organ were in a bad state. You could see green corrosion on at least one leg of all electrolytic filter caps on every printed circuit board. Most of the audio-coupling, and timing caps were visually and measurably okay, so they only got replaced if I saw they had a problem (either obvious corrosion, or had audible performance issues).
You could hear all sorts of swooshy noises–the low-frequency oscillators for effects, the whine of the tempo clock to the drumkit, etc. But replacing all the bad caps, and fitting 0.1 μF decoupling caps across all the digital ICs, and a few audio ICs, has eliminated most of that noise. And putting an insulated, but grounded, metal shield between the RHY and TG1 boards got rid of the final whine which seemed to be some heterodyning of clocks between those two boards (it's simply sitting between them, grounded to the tin shield on the RHY board).
There was also a slight burning smell always coming from the organ, even when switched off, so I replaced all the EMI filter components (caps and coils) on the mains input. They're actually before the power switch, so they're always connected to the mains. For as long as you've had the organ plugged in the wall, it's been putting up with mains voltage spikes, all day, every day. That's not kind to the parts, it's old enough that you should just replace those parts even if they seem fine.
When turned on cold (temperature-wise), there's a few moments of quiet mains hum (sinewave, not rectified AC). If cold and damp, it can be quite noticeably audible. Which makes me suspicious of one of the rectifier diodes, or even the power transformer. It has a very simple set of linear power supplies (for the amplifiers, the organ, and 7 volts ac for some panel lamps). The hum is consistent, no matter the position of the expression pedal or master volume control.