I bought a set at a garage sale for $1, and one has a broken plug. If I can figure out how they work, maybe I can fix it.
The cable that goes into the boot has 8 wires; they are soldered together in three groups of 3-3-2. The power supply has three prongs. It also has a dial with 5 settings. I tested the voltage on the power supply. One setting is off, and the other four have 2.7v between prongs 1-3 and 2-3 and
0v between 1-2. So the neither the voltage nor the contacts change with the setting. (The power supply is marked 2.4v)So, how do you think this works? What changes when you change the dial setting? What is the difference between prong 1 and prong 2? Is it reasonable to assume that 3 wires each go to prongs 1 and 2, and the other 2 wires go to prong 3?
I did contact the manufacturer and they said they don't support old junk.