Quoted from Atomicboy:
I'm amazed people are going this route. Most situations where a coil has stopped working comes down to a simple broken wire somewhere. All the things I outlined should be the first simple checks before short the transistor (which does have some risk if you screw it up).
I agree. Test firing the coil by grounding the transistor is fine if you do it correctly, but do it wrong, and you can really mess things up. I'd at least test for power at the coil first.