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

Just a follow-up to my original posts. I called the Deere dealer after not hearing from him for a week. He still doesn't know how much it will cost to fix and whether he can do it. He says the water pump and cam are shot which is not surprising at 1400 hours (especially with plastic cam parts) but he also says the crank shaft is shot which sound dubious. He said he would call me back when he knew, but when I called him back to ask how much a new tractor was, his voice brightened considerably and he had the sales rep on the phone with me in 2 minutes. Given the chimera that will result from cobbled parts, we'll probably purchase a new x720. Thanks mownie 7, I believe you had it right in that the water pump was worn and potentially leaking into the engine (I did need to top off the coolant from time to time). Who would suspect that a water pump could cause the entire engine to go (if the dealer is telling the truth). Also, a water pump failure would cause the temp gauge to rise while the engine continued to run. I still think crank shaft replacement is dubious, but he has me over a barrel and clearly wants to sell a new machine. Ultimately, I had 11 exceptional years of service from this machine. I worked it hard and it never complained. I'm still a Deere fan in spite of NYC service deficiencies.

Do you have any dash lamps that normally light up when the key is turned to the RUN position before you turn the key to the START position? If so and none of those lamps are coming on now.......your key switch may have gone defective, or the wiring connector on the back of the switch may have become loose. The absence of the fuel pump operation may also be an indicator of a problem with the key switch, but not proof of a key switch issue. Be cautious in using terms like "Everything under the hood appears to be fine electrically" unless you are checking things with a 12 volt test light or a DC volt meter. The naked eye is a poor judge of things electric except for identifying burnt or broken wires. There may also be a relay involved in supplying 12 volt power to the primary circuits on this machine. Failure of a relay, or a defective control circuit for the relay.......can mimic other types of component problems. You are going to have to begin checking the circuits using a test light or a volt meter, beginning at the fuse and working next to the key switch for battery voltage. Hopefully it will be nothing worse than a defective key switch or the connector on the back of it.

There a lot vibration around clutch pigtail wires look for broke inside insulation it be real easy bend insulation if broke inside. all safety switch need work to supply ground to clutch. You check this jumper wire to ground setting in seat are adding 50 lbs in seat should close switch. You turn key on electric should clich clutch never start engine just key on. I add video link how check clutch meter. And how adjust gap to .012. https://www.youtube.com/watch?v=wH9tZl6GzE0