Thanks to everyone for their input on this. I'm pretty sure this trailer has original parts from 2004, due to the fact it was rarely used. So, it may be that it is a caliper problem, especially since I am having difficulty on one side only.
How big of a job is it to replace calipers? I haven't done brakes yet, but have done lots of other things on my vehicles including replaced multiple starters, adjusted valve lifters, etc. It seems that the job should be pretty straightforward but I don't want to assume . . .
186,000 miles per second - - - not just a good idea, it's the law.