Briggs 28hp cylinder #1 not firing tried everything can think of

Hello all.  Hoping you can help me.
 
2013 Ferris mower with 28HP briggs and stratton Commercial turf v twin engine. 191 hours. 49L977 0125-G5.
 
I completed mowing 1.5 acres. Disengaged the mower deck and came back around the house and proceeded down the hill.  Heard a loud PING and then rough idle. I quickly shut it down and simultaneously verified the deck was off.  Yes. It was. It sounded like I hit something the ping was so loud. Hubby came around from back, he heard the ping.  He was able to restart it and drive it into the barn. It ran really really rough.
 
Thinking I blew a rod he removed the valve covers and all is in tact on both cylinders and manual rotationofthe flywheel shows the rockers operatinging smoothly.
 
Testing began.
1.  Remove cylinder 1 plug.  Fired it up.  Cylinder 2 is running.
2. Removed cylinder 2 plug. It turns over only like it's getting fuel but no spark. Cylinder 1 is not running.
3.Test cylinder 1 plug for spark.  No spark
4. Remove some stuff to get to the ignition coils. 
5. Remove cylinder 1 coil and ohm tested OK. For giggles and kicks we installed it in cylinder 2 and it fired up.  We took known good coil from cylinder 2 and put it in cylinder 1-no spark. End Result: both coils good.
6. Reinstall coils and  disconnect cylinder 1 kill wire.  Check for spark. Yes.
7. Recheck for spark with kill switch plugged in.   Yes spark.
 
Now I am at a loss with respect to a flow chart of testing.
 
I need help please on where to focus my efforts.
 
Many many thanks in advance
Elizabeth