I was working on a 21 hp, Intek B&S single cylinder. Got a couple coils from Amazon that were supposed to fit the engine I have. One only worked for about 6 weeks, the other only a few minutes. I ordered one from e parts tthat came in a b&s box that works. Looking on internet on how to test them. The one that failed first showed a resistance around 10,000 ohms.One I got that worked a few minutes showed resistance of 5,600 ohms. I didn't test the b&s one before installing. What resistance should coil show? Magnet on flywheel seems to be strong. does resistance depend upon flywheel magnet? I don't work on small engines unless I have to, but need some guidance please.