Small Engines (Lawn Mowers, etc.): briggs & stratton 4.5 wont start, spark plug gap, briggs stratton

Question
The flywheel does still have the magnets.  What am I looking for when you mention "flywheel key sheared?"  Are there any other wires besides the stop wire and the wire from the coil to the plug?  I disconnected the stop wire at the stop assembly (sorry about my terminology...it has a little brake pad that hits the flywheel when the hand lever is released).  Is it better to disconnected at the terminal post on the coil to rule out the stop wire causing a ground out?

Thanks in advance!

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The text above is a follow-up to ...

-----Question-----
I have a Briggs & Stratton 4.5, model 10G902.  About 2 weeks ago, I was unable to restart the mover.  I had been using it for about 45 minutes and whad stopped for a refuel.  In the past, I have replaced the spark plug on a regular basis (at least once a year).  I am mowing brush in a sandy area so I have to clean the air filter regularly.  Found your website and was able to determine that I am not getting a spark (unscrewed the plug, held it against the motor body, pulled the starter cable, no spark).  I have disconnected the stop cable, no luck.  Tried 2 new spark plugs with a gap 0.03, no luck.  Replaced the armature magnetto, no luck.  Do you have any suggestions?
-----Answer-----
spark plug gap  should be .030.  now you say you have replaced the coil?  and you still have no spark?  hummmmmmmmmm !!!!   i,d say you best back track.  first of all  does the flywheel still have the magnets in it? and does it still have power to it?  see if a metal object attaches to it.  if thats fine,  check see if flywheel key  sheared. if so replace it.  if all of that is fine,  and your sure the magnetto is good,   you need to check for something grounding it out> a wire pinched? etc.  to me it seems it is somewhere and it is not letting it fire to plug.

Answer
if you have it at flywheel brake disconnected, that should be fine.  it can not touch anything at that point. not the mower or any part of.  now understand this is just to test for spark, cause if its running it will now have no shut off unless you ground that wire to metal. is there also a throttle shut down by carb.? if it is in off > it too may  ground out to shut down at times there is both.  and the flywheel keyway i,m refering to is under flywheel hold down nut. to repair that flywheel must be pulled off.  what that does is keep the engine in time,  if magnets pass the coil at right time , it fires . if it is sheared,  the flywheel  tweaks just enough to  make magnets not in time with coil. sorry if it sounds difficult, it really isn,t >> but then again i go throught this every day and have the knowledge of.   if any of this makes sence, and checks out.  it should run. glad it worked out