Good point. In looking at manual (M116/M117 engine manual), the heading says for engines with CIS injection, and then has similar picture for 116 and 107. On quick look, it didn't mention the Djets (EFI). same in Section 1 for compression testing.
I recall Lefdje (73 107) replacing the harness that runs to starter via that terminal strip. And I have had mine partly out . Need to check wire colours and wiring diagrams to confirm if those terminals can be used for bumping.
Well, I would think that if any terminals can be used for bumping, they would get starting voltage when you start the car. If there are some terminals you want to test. I bet you could just measure the voltage and assure that it goes to 12+ Volts only when you turn the key to the starting position.
It would be great to know, but if you really want to eliminate everything but the starter while trouble-shooting, you probably want to go directly to the starter anyway. In my case, the wire that supplied hot to fire the solenoid melted because I cranked on it so much. If you are trying to bump the engine, it would send current though the same wire. If that wire is your problem (like in my case), you wouldn't be able to bump the engine when the problem occurs. So going directly to the solenoid would be my recommendation for best trouble-shooting. I think it is easiest to reach the starter wires from underneath the car. I recall on my w114, it wasn't too easy to make sure I was getting contact, but once I had the alligator clips attached, I never had to move or remove them, just assure the bump switch wires were out of the way of the exhaust and any moving parts. I left the switch laying on the frame behind the headlight and it never gave me any trouble. Granted, I never did anything more than driving it around the block a few times.