Starting a Mercedes Diesel ?

Factual Questions
1

I just bought a 240D here in the Philippines, and I am puzzled by how to start this car. To the right side of the steering column it has the normal ignition switch that only turns on the power to the car. To the left side of the steering column it has a large knob that you pull to start the car. You pull it about half-way to start the glow-plugs and then pull all the way to engage the starter. When I pull the knob to engage the glow plugs there is a light above the knob that is on, but never goes off, I would guess that the light should go off when the car is ready to be started ? But it only goes off after the car starts. Also, you can twist this knob left or right, but I have no clue as to what that function is. The car is supposed to be a 1985 model, but it is common for paperwork here to be changed. I am also pretty sure that this knob in question is factory, being American I am guessing this car to be a European model due to the gauges being metric. The previous owner is Korean and does not seem to know much more about the car, and his English is not so good either.
The car drives great, and was cheap, so I am not complaining, just curious as to this knob and the starting procedure for this car.

Thanks for any help !

2

In my 1978 240D you turned the ignition to the “run” setting.
The yellow/orange light came on. That meant the glow plugs are working.
When the yellow/orange light went off, that meant the glow plugs were done working, and you could proceed to start the car, much as you would a regular car.
In mine, one time one of the glow plugs burned out. It then started taking a LONG time for the yellow/orange light to go off… like 30-45 seconds, even in 60F degree weather.
Replacing the glow plug fixed that.
You might have a dead glow plug… or if not, then your model is older than mine, and maybe (speculating here) there is no “through glowing” sensor in the engine.
When I had one dead glow plug, it still started just fine any time the temperature was above 35 F.
You got a local Mercedes dealer? It would be amusing to call the service department and ask their opinion, although not neccessarily informative.