Good ideas to work on.
Another is many trailer mfg use some type of clamshell wiring connectors. Over time and miles water corrodes those connections to the point proper amps doesn't reach the magnets even though a dwell meter says 12v.
When I was on the road and put a new or used trailer in service the first thing I did was R&R the brakes/bearings/suspension and removed all clamshell connectors and bad or smallish wiring. I soldered all joints and made them water proof as much as possible. This ensures full amps from the controller to all the brakes.