Interesting set of events this weekend: car would not start, clicking sound, so I jumped started the 300D and took it for a drive; when I returned, I shut off and tried to start again; nothing, so I tried to jump start again, nothing, only clicking sound.
I tested the fan blower, windshield wipers, radio, and electric windows, and all worked; however, when I turned the key to start, all lights on dash went off, and the clicking noise persisted until a few moments later; then lights came on but no start;
I checked the ignition switch from behind, and found an oily substance; I tried a new battery, no results; I tried a wire from positive terminal to the starter block on the wheel well (the smaller of the 3 wires) and just a clicking sound; I tried to jump start once more, and heard a brief starter whirl, and then nothing.
I have ordered a new ignition switch, a voltage regulator, and the starter solenoid.
Is there something else I should investigate?