I'd check for a stick stuck in the works, or a broken cable. How about a lever thats rusted and not moving all the way? Better look at the linkage and pivots. And, don't knock Craftsman, before you find out that your trouble comes from poor (or no) maintenance! If it weren't for Craftsman tractors--there'd be a lot of folks pushing a reel mower, or a walk-behind mower! Or buying a billy goat!

I am waiting for the pto clutch which I ordered to come in. I took the old one off and it was in REALLY bad shape, bearing was about to come apart and LOTS if rust. They did repalce the voltage regulator but still not sure the old one was bad. It kind of sounds like you may have some wire issure in your pto clutch plug in. Even though the wires look like they are ok sometimes they are broken inside, I would check them out real close. Good luck

***"Mounted in plastic"*** Unless Deere has included some sort of "ring terminal" to the mounting, there is no need to separate the PTO switch from the plastic mounting panel. You said that the brake switch had been defeated before you acquired this mower and now the wires are taped to the brake pedal. OK, I don't see anything in the diagram where a defect in the brake switch could cause a problem in the operation of the engine that that occurs ONLY when the PTO switch is turned ON. By this I mean that any problem in the brake switch that could affect how the engine runs..........would affect the engine even without pulling the PTO switch to the ON position, so we can move on from that and go to the PTO switch itself. After studying this diagram at length/depth.......I believe the problem (engine wants to die when PTO switch is turned ON) can only be due to a defective PTO switch. And I think it must be because the PTO switch is bleeding some voltage into the magneto kill circuit which then upsets the normal spark making function of the ignition system. The way I see it, there are 3 ways you can test this: Option A, disconnect the wire pigtail from the PTO clutch and connect 2 independent, temporary wires to the clutch, be sure to maintain the correct polarity, Blue wire is the hot side, Black wire is the ground side. With the temporary wires in place, and the engine running, touch the temporary wire for the hot side of clutch to the "Battery hot" post of the starter solenoid (safer than the battery hot on battery). If the PTO clutch engages without affecting how the engine runs...........defective PTO switch. Option B, Disconnect (or cut) the White wire lead that serves the PTO switch (if you choose to cut, make sure you cut so it can be restored). With this white wire out of the equation, start the engine and turn the PTO switch ON. If the engine runs OK now, replace the defective PTO switch. Option C, Replace the PTO switch and hope for success.

Had the same problem with Cub C (MTD) tractor. Was the battery.