If you have voltage at the coil when the points are closed and none when the points are open, the switchbox is working. If you have voltage all the time, the switching transistor in the switchbox is probably shot. YOu can get a replacement at Radio Shack and solder it in, but you need to check the voltages first -- I don't believe you should have 12V at the coil with all the resistors in place.

If you get a spark by applying and removing voltage from the coil, it at least is good.

If the points go to ground and drop the voltage at the green wire on the junction to near zero, the points are good, too. If nothing happens (no spark) there is very little doubt the swithbox is bad. As I said, the usual cause is a bad high voltage switching transistor, and it can be replaced for very little cost if you don't mind opening up the box.

Otherwise, I'd go for a Crane or Pertronix system. The switchbox is VERY expensive, if you can in fact find one in working condition!

If you get a spark with the points hooked up directly, but no start, you may have a timing problem too -- make sure the timing is set correctly (a helper to crank the engine while you check is necessary).

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!