So, just to be clear, the main wire from the battery comes into the top terminal, and the wire to the alternator also connects to that top terminal. There are two small wires; a purple one which I assume is the direct line to the starter, and a bypass line for the glow relay. Nothing connects to the bottom (ground) large terminal.

Right...?

__________________
- 1979 W123 240D 4-speed, 390k miles