Repair Korg Delta Synthesizer Repair Service. This came in with the customer description: "my old Korg Delta causes massive problems: synthesizer section only rarely works and when it does, then only very quietly and noise no longer works at all".
At first glance, I saw what kind of work I had to do and that it wasn't just going to be just troubleshooting and troubleshooting. Leaking electrolyte is never a good sign. That's why you should have your synthesizer serviced regularly before the electrolyte causes too much damage.
The missing noise signal was due to the fact that a capacitor etched away the conductor track and thus interrupted the electrical connection between the noise generator and the mixer. I then recreated them with Kynar wire and protected them with solder mask. Of course the whole synthesizer was recaped. The malfunction in the synth section was due to defective OTAs.