When I made my initial repairs of the Wurlitzer I was only able to address some of the problems with the pedals. The pedals operate with the help of a magnet on the end of each pedal, which closes a reed switch when the pedal is depressed. Some of the reed switches were broken; at some point, someone had tugged on the wire bundle coming from the pedalboard hard enough to pull the contact out of the end of some of the reed switches. Replacing those broken switches was easy. Luckily they still make magnetic reed switches in the exact same size.
Even after those mechanical repairs some pedals still didn't play and others sounded wrong when they did. The pedalboard is interesting. It uses two frequency dividers to lower the notes produced by the pedals by two octaves. But it only has two frequency dividers, so it has to be monophonic -- only one note at a time can be connected to the dividers. There is a pedal latch circuit that does something clever with a 220 VDC power supply and neon indicator lamps to allow only one note's signal through, even if multiple pedals are pressed simultaneously.
This latch circuit defeated me. I could see multiple lamps lit, even with no pedals pressed, which I knew was wrong. But I couldn't figure out what the root problem was. Maybe all the lamps needed replacement, maybe something else was broken as well. I didn't want to spend time and money replacing components willy-nilly without understanding what was going on.
After I posted my article on implementing Newtonian trajectories in KSP last September, I started a thread in the game's official forums to discuss it and had some interesting conversations over the next few weeks. Ever since then I've been meaning to post a followup article to bring together some of the points from those conversations, but until now haven't managed to actually write anything. But finally, about five months later, I've gotten around to it! Here goes: