Please help electrical

My 1978 280sel, has been acting up, to the point where I couldn't get it started.Someone came over looked at it, hooked a wire from the battery to the coil and it started right up, his diagnosis, bad ignition switch.
I haven't replaced the switch yet , but the car still runs doggy, can barely make it up the drive when I took it for a test ride with the wire hooked up. I recently replaced the alternator, but I am totally stumped on this one, any help greatly appreciated!! Jim
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A '78 280SEL?
Seems like an ignition problem that's causing a very weak spark.
Suggestions:
1. Be sure the battery is fully charged, a (new) alternator doesn't guaranty a fully charged battery.
2. Assure yourself that the engine's ignition system is working correctly: That the distributor cap isn't cracked, that the rotor is OK and that the coil isn't cracked. That the ignition points (or whatever this engine uses to make and time the spark) are OK. Given your description, IMHO, you'll find the problem in the engine's ignition system.
3. Don't tear into the ignition switch before you're satisfied that the engine's ignition system is OK and that the neutral safety switch is working as it should be.
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Hi all, I have a 1978 280sel euro model, it has been acting up for awhile, its last thing has been not to start at all, a friend looked at it, hooked up a wire from the battery to the coil and it ran. Upon driving it this way, it has absolutely no power, can hardly make it up my driveway which is a slight incline. This all started when I had belt problems, and changed the altenator, which may or may not be related. I am stumped big time, could this be my ignition switch ? Thanks ahead, Jim
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