1974 Brain Box saves the day.
OK
@pishta, school me here.
I just cut open this failed aftermarket black 5 pin brain box.
To start off it was full of sand ????
Opened it up and that silver transistor on the external heat sink was not wired to anything, it was empty.
Looks like there were some cooling conductors from the main board chip to the heat sink on the inside, but no wiring there.
Imagine there is a small mother board with a computer chip in there like on a computer wired to the 5 pin plug.
What do you think ???