I have a Craftsman, Model # 917270821; 19.5 HP B&S; turbo Cooled; Auto-42' cut. The mower was running and mowing great. I turned it off and now it will not start. The engine does not turn over. I had this problem a couple of days earlier and replaced the blade safety switch. I thought this fixed it but the problem has returned. I checked all the operator safety switches to insure they are plugged in properly but to no avail. What am I missing?

Hi,
Well, the manual and wiring diagram are available online. First you need clean battery terminals attached to a serviceable battery. The positive side is connected to the solenoid all the times. The solenoid is tripped by the key switch supplying ground to the solenoid through the PTO (blade) switch, the clutch/brake switch and finally through the key switch.
Your battery is beneath your hood, so I would look suspiciously at corroded connections as the ones I have mentioned are mostly likely there in the vicinity, also.
Peace,
Clarke

Thanks for the great information crigby. I took your information and was checking the connections and came across a loose ground wire at the ignition switch. As soon as I tightened the connection it worked fine. I appreciate you getting back to me with your suggestions because I was at my wits end with this problem. Hope you have a great week.