Checking brakes on travel trailer surprised what I found

You might ask a moderator to move this from class A to travel trailer forum.

Before each season I jack up one wheel slightly off the ground, pull the emergency breakaway cable, spin that wheel, and make sure it locks up. If good, I put the cable back and repeat with the other three. If all good, then great. If one does not lock up, then I find out why and further check the others.