10k axle electric brake not working on one side, any thoughts

mid 90's big tex gooseneck with 2 dexter 10k axles

it has very, very little miles on it but the front axle has the original brakes. they are 12 1/4" x4"

the shoes (pads) on both sides have heaps of life left,, it's like they were not used,,

the rear brakes will practically lock up when my 2019 ford f350 dash image shows "3" it goes from 1-10. this ford has the brake controller built into the dash and when used, the instrument cluster has a digital graphic display showing how much brake is being applied.

but the front brakes,, the drivers side is still not locked up at "3" and the passenger side doesn't work at all.

the wiring looks fine and i checked the ground wire that goes to the frame it is good as well.

i can visually see the pads thru the gap of the backing plate and they are adjusted the same as the rear.

i have worked on electric trailer brakes before on 5th wheels. these 10k brakes are bigger of course

full disclosure, i have not removed the drum yet to check them out,,,i ordered some oil seals (these are oil bath hubs) because as long as i have them out i will replace seal. it's not leaking but it must be old.

appreciate any input

 

i was under there while i had son push controller and i could hear them humming,,, maybe i have old ears but was hard to hear which one was humming, however, it did seem like the one that was not working was not humming or had diminished humming at least.

 

the guy i bought the trailer from,, had replaced the rear brakes already just to make it back from missouri where he brought the trailer from (he at least knew the original owner, cousin, and how he used the trailer) but he had bought both the front brake assemblies and included them with the trailer so i guess it's an easy replacement i was just hoping i could adjust the front ones.
i was shocked when i looked online at the prices of the brakes,, they were 600-700 for a pair.

my fifth wheels did not seem to be that expensive,, i guess prices have gone up

 

when you say buy new backing plate,, you mean,, but the entire assembly together rather than just the magnet? assuming it is magnet?

 

wow,, i haven't seen that anywhere,, where was it?