Small Engines (Lawn Mowers, etc.): B&S 21 hp no fire, switch problem, armatures

Question
I have a Murray 46in with the B&S 21hp intek (model 406677). It is only three years old. The question I have is that it will turnover but not fire. I have put a new battery on it, new plugs, new fuel filter.It doesn't seem to be getting any fire to the plugs. Since it has two spark plugs with the two armatures, could they have both gone bad at the same time? What is the best way to test them?

Answer
Most likely they did not fail.  There is a wiring harness connecting the coils that contain some diodes.  Once in a while these will fail.

To check the coils, dis-connect all the wires connected to them.  Remove both spark plugs, crank the engine and check for spark.  If you have spark, then either the harness connecting the coils is bad or there is a safety switch problem.  Do you know how to check diodes?
Let me know.
Eric