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Mercury used quite a few different stators in those years, but here are resistance checks that you can perform with your multimeter. If you have a DVA adaptor for your multimeter, you should also take voltage tests, as this is the best way to check it.
1. Flywheel with magnets glued in
Blue to Blue/white - 3250-3650 ohms - 100+ volts when cranking
Red to Red/white 75-90 Ohms - 25+ volts
2. Flywheel with magnets bolted in
Blue to blue/white - 5000-7000 ohms - 100+ volts
Red to Red/white - 125-155 ohms - 25+ volts
3. Red stator
White/green to green/white - 500-700 ohms - 100+ volts
Blue to blue - OPEN no resistance 0 100+ volts
Blue (each) to ground - Same as above
If your stator fails any of those tests above it is no good.
Also check your flywheel for broken magnets.
Post back with questions.
Then you would be looking at a bad switchbox/powerpack,(same thing, different folks call it different items) Or, multiple dead triggers on the timer base.
The switchbox would be the most common items. It is not common to have multiple triggers die all at the same time.
Switch box's by themselves are not directly testable. To test them, what we check first is voltage input to the switchbox from both the stator and the triggers, then we test voltage out of the switchbox to the coils. If all of the voltages in are good, but the voltages out of the switchbox to the coils is bad, we can deduct that the switchbox is bad.
To test voltages, the only way to do it is with a multimeter with a DVA adaptor.