I just bought a used craftsman mower, dark green model 917 I think, the battery was dead but the guy had charged it before I came and bought it, it started right up sounded good I bought it, got it home, charged it a little, started right up, tried out some of the attachments that came with it. Battery would not hold a charge, mower belt was old slipped when putting deck down in heavy grass. Anyway, bought new battery, and belt, installed them, changed the oil, filled the gas tank, used it a little, drove it back to the shed, lowered throttle to idle, engine died, won't start, good battery, turns over fine, gas seems to be getting to the spark plug, but I can see no fire on the spark plug. Help, I have no experience with craftsman mowers, no owners manual, is there some kind of safety switch that would allow it to turn over but not start. Sorry if the question seems long, any help would be appreciated.

Okay, so it was running until you made repairs?

Yes, I was able to start it, at first, even with the bad battery. I would hook it to a charger for a few minutes, disconnect the charger, sit in the seat and start it right up. When I would shut it off the battery would be dead again, but each time I charged it a little, it would immediately start right up again. After I changed the battery to a new one it worked just fine, starting right away again, but when I drove it back to the building, I pulled the throttle back to the idle position and the motor died before I shut the key off. I thought that was odd, so I tried to restart the engine, with no luck, it spins the motor but does not hit, removed the plug, appeared to have fuel on the plug, put the wire onheld it against the block, can't see any spark. What should I check?

A safety switch. Find the complete model number and look up here at Parts & Accessories | Shop & Find Lawn & Garden, Appliance Parts at Sears Parts Direct | SearsPartsDirect.com from Sears and find where the safeties are.

I have now replaced the spark plug and the safety switch under the seat, still no spark, no hit, no start, just turns over and over, what next?

Remove the blower housing and see if you can remove the small black wire from the coil, then see if you have spark, if so, the wire is grounding out somewhere, if not, the coil could be bad.

Briggs dealer told me a minium of 350 RPM is need for mag to start making spark. Maybe starter not spinning engine fast enough. Just saying. I am no expert.

1st remove spark plug wire from spark plug,remove spark plug from engine,plug wire back on to spark plug,now turn engine over like you are trying to start it, watch to see if you have a spark at the end of spark plug! If you have a volt meter handy? Remove wire from end of spark plug attach ground wire from v.meter to lawn mower engine,touch Positive wire from v.meter to end of spark plug wire.Set v.meter to DC spin engine while watching meter if no response try replacing coil which is at the other end of spark plug wire.