Mowing Blown fuse

[BrokenAxle46]

I have a John Deere 430 garden tractor (20hp) with a 60 inch belly mower that blows 25 amp fuses after about 20 minutes of mowing. I let the kids use the mower and they leave it outside all summer. I bring it in after fall and store it all winter. Had put a new PTO clutch assembly on about 4 years ago. Everything worked fine until this spring. Clean it up, change oil, grease and general fix anything needing attention then mow to be sure its OK before letting the grandkids get it.
This spring it fails the test after about 20 minutes of mowing, it blows a 25 amp fuse and kills the tractor, replace with a new fuse, tractor runs but will blow another fuse if I kick in the mower. Took mower off run tractor without any issues. Checked wires, cleaned and put electrical grease in the connectors, same result. Question is, could the PTO field coil be shorting out when the engine gets hot? Since it engages when I hit the switch, the coil is working but how would I test a short in that coil when it's hot, I know it will pass a cold test because it does that on the tractor now. I like the 430 model and plan to keep it, also have a JD 2320 (24hp) and I simply love that tractor, also have a JD 312 (12hp), so I have other mowers but like the 430 to keep running and in good shape. Any suggestions would be appreciated.

 

[Fawken]

Had a friend recently who's MTD kept blowing a 25A fuse killing the motor. Turned out to be a headlight wire that had become frayed and was shorting to ground when the right circumstances of vibration, lawn pitch and rider weight presented themselves.

 

[BrokenAxle46]

"Turned out to be a headlight wire that had become frayed and was shorting to ground when the right circumstances of vibration, lawn pitch and rider weight presented themselves."
Thanks, worth checking into. I am thinking of going through the entire tractor wiring system one wire at a time. Heat seems to be the trigger so I have looked for obvious wires but didn't find any so the next step is a complete wire by wire search. I am guessing it's something of this type, more frustration than anything but in the end, I do enjoy tearing into problems. This is another time and patience issue, I have a lot of patience, I just don't have time to use it!