Is the wire coing from the ignition switch have 12 volts wen the key is on, or is it just a groudn signal? in a service flash bulletin (division 32), it talks about the ignition switch.the tractor was obtained used, but in the tray under the seat was an old ignition switch. tractor did run, but lost spark. also the fuse link was broken, but the fuse in its holder is okay. I do not have any manuals to go by, but only a bulliten on the website about the ignition circut. the tractor is either a 1969, or a 1970, body model # is 917.25511 and engine model # is 143-602022.

In general, the older tractors used the switch for grounding and as a starter energizer.

Check the ground wire that goes to the engine shroud. Sometimes, the insulator grommet will get messed up, letting the circuit ground.

You may need the services of Ed Stoller on the Sears Garden Tractor Group on Yahoo. He's the guru when it comes to ignition problems.

Here's a link to a generic ignition diagram. Probably the same one you already have:

http://photos.bravenet.com/426/001/687/3B71FC3827.jpg

after i checked the wire coming in from the switch, I found that the wire was hot when the key was off, and ground when the key was on. so then i checked the same wire to make sure it wasnt grounded through the motor, and that was ok. i called lawnmowers unlimited to get a price on a coil and magneto. they said it was discontinued. so then i came back onto the site here, and punched in garden tractor boneyard. i called up Ray' mower service, the lady was very helpful to me and said that they had used parts and would test them out on an engine. i bought a coil and magneto and also a float bowl and manual for the engine. the lady at Ray's mower service called me back to tell me that they found parts and would test them out. Then send them to me through UPS. and since then i have bought a gas tank rear fender and headlights from there. (this place is the best place to get parts, they are so helpful and courteous) Now my 1970 sears suburban is running as good as new, thanks to Ray's mower service ad your helpful website. thank you spence for your help as well.