I have a Sears Craftsman Model Number 917.259572 which ran fine, then turned it off, then it won't start. It turns over fine and I replaced the armature-magneto and battery but still no spark. I cleaned the spring contacts under the seat. I pulled apart the connection under the seat and tested the switch. I get continuity when the switch is doing nothing and an open circuit when the switch is pressed. However, (I don't know if this means anything), but I put the switch only halfway in the socket, and put my ohmeter leads on the switch leads while they were in the socket... and get continuity regardless of whether the switch was pressed or not. I cleaned the 30 amp fuse(?) contacts. It is a fuse that has solid flat contacts that slides into a socket. I put an ohmeter from the thin wire on the armature-magneto to ground. When the key is off, there is no continuity. When the key is on, there is continuity. I understand there are two more safety switches, but I don't know where they are as I can't find a logical connection to the brake or the blade engagement. What else should I do? Thanks in advance.

Put a little gas in the carb see if it starts. If it starts , check fuel solenoid on carb.
Luck

I have no spark. It won't start without a spark, regardless of whether there is gas in the carb. I need to know what is preventing the spark.

How did you test for spark did you use a inline spark tester . Or did you try the old trick of using a screw driver , or are you assuming it doesn't have spark because it won't start.
If its cranking that most likely means you safety switches are working,what did you gap the air at on the coil / amuture.if the fuse was bad it will not crank either.
If I knew what motor was on here I could probably give a little more info, unplug the little groung wire going to the coil / amuture if it starts check for a bad spot on , or unplug key switch and jump solenoid if it starts check out key switch ,this could be going to ground. Luck
PS don't forget to come back and give me a good mark when you find out its not getting fuel.

DG:

Thanks for your responses...

1. Yes, it is cranking.
2. I tested the spark by holding the spark plug tip against the engine fin while the spark plug wire was attached and it was cranking. I also removed the spark plug and held the spark plug wire by itself close to, but not touching, the engine while it was cranking.
3. The engine is a Briggs & Stratton model number 42E707, Type Number 2631-E1.
4. I did put fuel in the carb and cranked... but it didn't start.
5. I unplugged the thin wire on the armature-magneto and it did not start.
6. I did not gap the air on the armature-magneto... it looks like it is self-contained. It is part number 333 on Sear's diagram.
7. Can you explain how to jump the solenoid... and whether this would prevent a spark?

Thanks again.

There is a magnet on the flywheel ,you should gap the coil here , if its to close no spark if to far away no spark,
Take a business card put it between the flywheel magnet and the coil loosen screws on coil and let the magnet suck it in , tighten screws gap should be good.to jump solenoid make sure brake is locked safety first ,
The two big post on the solenoid cross them with a piece of metal careful not to burn yourself.
You might check the wire coming to the coil and see if it has a diode in it , if so it could be bad,
If it's a new coil it could be to far away from magnets.
Did you replace it with a new one ?

By the gap, I am assuming you mean the gap between the armature-magneto arms and the flywheel. I'll adjust that gap later tonight and get back to you. Yes, I replaced the armature-magneto with a new one.

If the solenoid is bad, it wouldn't crank at all, would it?

I unplugged the thin wire to the armature-magneto and tried it and it did not start... so it can't be anything to do with that wire.

Yes the arms of the armature
And right if its cranking the solenoid is working.
Luck

So, I adjusted the gap between the armature-magneto and the flywheel, and it started right up! Woohoo!

Now, I feel like I should reinstall the old armature-magneto to see if it was truly bad and confirm that this was the reason it stopped in the first place, because everyone I talked to said these things don't fail... but I figure the thing is working, so I'll leave it alone and consider the $55 spent on the armature-magneto as money well spent.

Glad you got it going , don't forget the good mark now :)