gremlins......common or different problems

[JackG]

It all started with the car (coupe W123) not shutting off.
Within a few days, it wouldn't start with the key. Now
it is getting really hard to start, but seems to be turning
over just fine when jumping the box on the fender well.

After jumping it with the bimmer(oh the shame) to increase
amperage, it did fire off this morning and I pulled the battery
@ work and tested it on the mac tester. It was at 12.79v
and 663cca.......is this enough?
It is giving the impression that the glow plugs are not
working as they should, but the dash lite cycles as it should.

Is this an ignition switch problem? or multiple problems?
any way to test the ign. switch?