***"sometimes when trying to reengage the PTO or engage the transmission it will kill the engine"*** Sounds like it may be related to a safety interlock switch, or a relay that is part of the safety interlock circuitry. Is your PTO hydraulic, controlled by a solenoid valve? If that is the case, a defective solenoid valve might be overheating to the point of "going open" or even "shorting out" after it has been energized for the 20 to 30 minutes of operation. But, sometimes relays can act up when they are overloaded by too much current draw when they get old, or, if the device they are controlling develops too much resistance or "shorts out". When the engine "kills", will the engine crank right back up? or does it act like the battery is weak or dead?

RD, you are talking apples & oranges here sir. 425 & 445 features a gear type PTO system where the PTO shaft emerges from the front of the rear axle case to power a gear driven MMM deck. Markwisz, you see smoke coming from the two wires that go into the rear axle housing. You have located the wires that power the PTO solenoid. Most likely the solenoid has shorted internally and will have to be replaced. The fact that you see smoke might be proof that the solenoid coil wiring (which is very small wire size) has shorted and burned up. But, it might also indicate that the OEM fuse for that circuit has been replaced with a larger ampacity fuse. Whatever you find regarding the burned out PTO solenoid, please double check to confirm that the fuse has been been replaced with a higher capacity fuse. Fuses are meant to fail when an electrical short or overload occurs. That fact makes me wonder why you are seeing smoke as the second indicator (mower quit being the first) of trouble instead of finding a blown fuse, and that fuse blows again and again when you replace it.??? It could be that the wires that are smoking are too small to blow the fuse in the particular place of the coil the short occurred, but it could be due to a heavier than spec fuse having been put in place at an earlier time (time bomb). Here is a link that might be useful: 425 PTO solenoid

All done! Actually, it was a piece of cake. I didn't need an impact wrench at all but I did borrow a set of ramps from a buddy and that made putting the clutch back on a little easier. I used the third option suggested by Mownie and just had my wife hold the flywheel with a wedge while I loosened the bolt. It came off very easily and took just a few minutes to swap the old one for the new one. While I had it part I replaced the drive belt too and that actually took longer than swapping out the clutch! Another benefit was I found an online source for parts for my tractor that runs about 30-50% less than what Sears charges. I can't believe how much I could have saved over the last 6 years on maintenance parts alone! Thanks so much, Mownie and Walt! The repair was minor but I might not have tried it without the confidence provided by being able to 'consult' with you guys when I had a question.

You will have to verify if there is power to your clutch in the off position first to determine if it is electrical or something physical w/ the clutch.