Volvo Repair: 83 244 DL wont start, coolant level, hall sensor

Question
Hi, I bought an '83 244DL (not turbo) two years ago and it has been a great beater.  No real problems at all until I was at a stop light last week and it just turned off.  Since then it has not restarted.  When I turn the key the engine turns over but won't start.  Previous to this it had been shuddering hard right after starting or sometimes required 2 tries from cold.  Also it has occasionally been running hot (not red), but coolant level was good.  I can't think of any other symptoms.

I took it in to a local Volvo mechanic I've dealt with for minor things (brakes, etc).  He poked around and said there is no spark in the distributor.  He tried replacing the Hall sensor and that didn't work.  Now he says it's probably the cable harness but doesn't want to replace it because that would cost quite a bit.  From his instructions I opened up the harness as far as I could without taking off the intake manifold and all wires seem good (he thought they would be pretty bad).  He seems stumped and I definitely am.  Please help, I don't want to throw away this great old car!  Thanks.

Answer
Trevor, I hate to think that he missed a possible timing belt breakage but that would be something I would check first. He is correct on the harness.  That is definately something that would cause a no start.  The Ignition control unit is also a possibilty.  Without doing my own tests, its hard to pinpoint it just by giving suggestions.  Roger