The odd thing here is that he has had a shop determine a starter that was installed was bad, and he has used a remote starter switch to check the system out and got a "no noise" response. The remote starter set up should bypass the transmission and key interlocks, shouldn't it?

It sounds to me, if the starter is "good," like the starter mounting flange or the bolts, through which a ground is usually made, are painted or not grounded somehow. Or he could be getting bad starters with internal grounding or power connection problems that only show up after the stator rotates a little in its frame. Edit: The stator is not supposed to rotate in its frame, as it is supposed to be keyed or have some other means to transfer the torque reaction to the mounting flange bolts. If this is not a suitable keyed fit, or there is a damaged part and a little movement is allowed, the integrity of the internal and external electrical connectors can be compromised. It is feasible that taking the starter out agitates it enough to allow the connection to be sound enough to withstand the starting/accelerating torque, so it works on a stand. Installed or loaded, the additional current demand and toque produced might simulate the conditions in the car better.

When my last starter replacement on the 240D was undertaken, the old starter had some internal structural failures that made it respond very much like is being reported here. NO sound. But I knew I had beaten the starter to death with the broken engine mount. When I took it out it was not a sound assembly. The connection end was loose, not falling off, but not tight. But it was electrically damaged as well, on the inside. Since I wanted the core value, I shipped it back "whole" so to speak, meaning not in pieces.

It also makes little sense, without some additonal data, that his key and/or starter interlock with the transmission would crap out and then be fixed by rummaging around with the starter. It seems like replacing the starter would have little to do with fixing a key problem or interlock problem, even temporarily.

I have another question, does the starter ever work intermittently, or when it dies is it dead for good, until you take it out and give it to the shop to check?

Well, this is another interesting mystery. Good luck, and keep us posted with the results. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)