Good news, I guess. I finally resolved my brake issues on the trailer after almost a year. When I originally got the trailer and completely replaced the brakes, I had some 2 strand, 10 gauge wire which was perfect. But I only had enough to run from the junction box to the left wheel so I reused the original wire zip tied to the axle to power the right side brakes. Recently I opened up the brakes and it appeared the self adjusters were broken, so I purchased complete new brake assemblies (Dexter this time instead of Lippert). The new ones adjusted out fine but still didn't stop the trailer. So I pulled the drums again thinking they might be glazed and sanded them with my 4.5" grinder and a 60 grit flap disc. Reassembled and still no brakes so I purchased another set of new drums (again, Dexer instead of Lippert). I'm into these brakes for well over $1000 now and still no brakes.
Yesterday I added an additional ground wire and ran a temporary second power wire from the junction box to the left front. After driving to a job I smelled brakes, the left was hot and the right was cold. So this morning I jacked the trailer up and replaced the 2 wires running across the axle. Maybe one was rubbed thru and grounding on the axle, maybe they were just corroded inside. But with that simple repair I now can lock up the tires easily with the controller.
I'm looking forward to seeing how the trailer handles loaded with working brakes. Now it won't be so hard on my F150 when I use it to pull the loader.