I rebuilt a Serge system for a customer. There is a lot of good information on Serge at www.serge.synth.net/.
The top module was well built and only required determining what the modifications were.
The lower module was very poorly made, had a number of modifications, and several modules did not function. I completely rebuilt the lower panel, repaired modules, replaced intermittent potentiometers, removed a number of modifications, and rewired about half the panel. This panel also includes the Noise Generator-S&H module and is wired to the banana jacks and switch on the far left. After this photo was taken I reused the two plug holes on the far left for the white and pink noise and added VC attenuators to the Wave Multipliers on the right as can be seen in the system photo.
Because it was such a spaghetti of wires, I chose to wire power to each module separately so I could focus on just getting that module operative. I then made a power distribution board and wired all the modules in a star configuration instead of daisy chain. The second SSG20 SSG20 Smooth & Stepped Function Generator and the Noise Generator-S&H modules are piggybacked on the rear.
The keyboard consists of the keyboard and QUAN module. One of the LEDs was dead which required removing the touch PCB to access the rear-soldered LED. The keyboard was also built with sockets that fractured and lost tension with the IC pins. Replacing the sockets restored operation.
The rear of the system is quite clean with a small power supply.