Hello, I have spark but no start. Changed oil week ago, started right up. Now nothing.
What I have done:
Checked all kill switches and ignition switch = good, have continuity both NO and NC
removed kill wire from coil
coil didn't test great with multimeter so replaced coil
Replaced interlock module as didn't know how to test
Removed carb and cleaned thoroughly 
Took out new fuel filter and put in straight connector to ensure gas getting to carb (just for testing)
Throttle appears to move the arms to the carb properly
 
Won't fire even with starting fluid. The only things I can think of now are loss of compression, but it was running fine only recently or maybe timing? 
 
Thanks for any ideas!

Try disconnecting the small kill switch wire attached to the coil- 
Lets eliminate all possibilities of most electrical components.
 
Are you checking for spark at the spark plug, grounded to the head, visually seeing it?
 
Is fuel from cranking making it into the combustion chamber, IE  a wettish plug with fuel?
 
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Thank you for taking the time to reply. I had my wife pull the cord while the plug was grounded. I had spark and even "bit me". The plug is wet on the end. The plug was good per ohms. I have the "kill switch" disconnected from the coil and not grounded anywhere. I even jumped the safety switches individually except the one that's both no and nc at the back but it tested fine, continuity, in both positions. 

Check the compression and or a "load test"...
 
You can also remove the flywheel and check the keyway, that it's not sheared..
 
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Thank you. I have a compression tester (somewhere). Hadn't thought out the key on the flywheel. I just totally rebuilt the engine in my old project car from a bare block, yet this damn lawn mower might have my number :)  Again, thanks for taking the time to reply.

Sure.  Plz post back what you find..
 
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Yes, sir. Will do.