You need the replacement trigger, not the ignition coil, right? I've bought these from CDI Electronics, Inc. in the past.
12) Trigger Voltage can be checked with a voltmeter set on the 20 VAC scale.
Place 1 voltmeter lead on the switch box trigger terminal and the other
voltmeter lead to engine ground. Voltage should be present; if not, reverse
voltmeter leads. If voltage is still not present, trigger is defective.