When not hot, my 1994 940T always cranks and starts well using the ignition switch. On hot days after being driven, turning the ignition switch will not get the car to crank. The idiot lights will dim a little, and I think the starter solenoid moves a little, but not enough to make good contact and crank the engine. When I jumper the solenoid it cranks strongly and starts, every time. The battery is new, the ignition switch (behind the key switch) has been replaced, and it has a rebuilt starter. I have not replaced the neutral safety switch. Again, the failure to crank only occurs when hot and attempting to start with the key. Jumping the starter solenoid always cranks the engine in this situation. I suspected a bad wire termination at the battery, but putting cold water on those connections makes no difference.
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john