The 74 is wired different than the ones that followed. You've got two wires at that terminal, all the rest have only one. That's why those instruction don't make sense.
The fact of the matter is your alternator isn't charging. And the first suspect is normally the rotor. In this case the brushes are obviously making contact and there is a flow through the rotor to ground. Normally the rotors fail open, but they can short circuit as well, and that's what I suspect in your case.
What you need to do is measure the resistance between the slip rings with a good ohm meter. insulate the brushes from the slip rings with something nonconductive, like a bit of cardboard. The rotor should measure 3 ohms - something in that range. If it's zero, that's the culprit!
Wanted: Dead, smashed, crashed or trashed gauges
BMW GAUGE REPAIRS - TACH*SPEEDO*CLOCK*VOLT METER *PODs & LIGHT BOARD*