[BILL WILLIAMSON]

Coils RARELY fail, it's usually the crap that controls it that goes AMUCK!
Using a cheep test light & getting used to how BRIGHT it glows on a GOOD source, is your BEST, QUICK Friend.
You CAN'T screw something up using it!
An inexpensive Multimeter is better. They're not SPOOKY to use, PLAY with it, read the instructions, find a "U" tube video on its' use. You can "play-like" you're an EXPERT & impress folks. Lurn some ELECTRONIC sounding wurds & terms & they'll want to HIRE you!!!
Even an OLD Encyclopedia can help you with some BASIC electrical knowledge.
Bill Babble