Well, I'm reasonably certain there are dozens of YouTubers who figured it out. I wouldn't be surprised if I could figure it out myself, although it's unclear. But yes, repairmen, they would not be replacing a single relay. They would replace the whole board if it's available. Otherwise, the whole thing is scrapped.
Repairing a relay is something that's easy for someone to do by themselves. However, it is not worth it for repairmen. By the time they get the relay, which means a second trip for another $150, plus spend the time to unsolder it and re-solder it, so a bit more of their time, so now we're up to $400. Worse, they replaced the relay and sometimes it turns out the relay failed because something else is broke and another thing is just going to break the new relay right away and now they have to spend another $150 on a repair trip to figure out what was wrong that caused the relay to burn out, replace that part and replace the relay. We are very close to the cost of a new washing machine right now and that is assuming whatever is wrong is easy to repair and not the result of something else that is also broken. Thus, the right answer for a repairman is you make the simple, cheap, quick fixes you can or you just sell them a new one before you end up wasting more of their money than it
Modern factories are very efficient at making things, however, that only works when the assembly line is there. A repairman working alone doesn't have all the advantage of a factory. I was recently talking to one of our factory engineers at work and they said this part, whatever it was, took two 'man hours' to build in our factory. But a repairman just taking it apart to replace one cheap seal and putting it back together would be at 10 man hours. This is why more and more things are going to modules that can be replaced. If a repair person can come out and look and say, this module is broken, grab a new one, shove it in, and it works, they can be in and out quickly and it's cost-effective. If they have to tear down to the relay level and diagnose things if you're at why it really broke, that quickly becomes more labor and thus more cost than it's worth.
Your devices in the 1960s did work and they were worth repairing because they were a lot simpler. Those devices also didn't have nearly as much automation in the assembly line and so there were many more man hours to build in the first place. They were also, although this is less true depending on what we're talking about, but very often had unreelable parts that because they were broke often, they specifically designed those for your parable. You fixed a 1960s TV by replacing all the tubes, something that was not very hard to do because they put more expensive sockets under each tube to make it easy