Oh boy. This entire thread sounds so similar to my own brake issues with hull #110. Nearly two years of doing similar checking & replacing. I should have just listened to others on this forum from day one, and pulled BOTH brake wires from the axles. Did I do BOTH at one time? Of course I didn't, I'm a nuckle-dragger. I got stopped by rain after finally pulling out and replacing the wire on the rear axle (this year), then still having brake issues with the truck, I finally got to doing the front axle. OMG!!! The wire in my front axle was an ABSOLUTE frayed mess in several locations.
Once I had both new wires on the outside of the axles, I've not had an issue since. Now towing with my new-to-me 2024 F-250. No issues.
But, I will say, doing all that troubleshooting and replacing 7-pin connectors and inspection the 7-pin wire connector to the trailer and redoing connections a few times.... well, I'm much better and braver now for it.
WHEN the next person inquires about intermittent brake issues. Please have them pull BOTH break wires from the axles and save them many hours of troubleshooting. I think it should be the first step after checking basic voltage at the break assemblies. Just my 2cents.
I have a thread around here about that "saga".
@Boudicca908 I hope you're all fixed up now. I may have lost track in all the good info in the thread.