I had a similar problem with the brakes on my new-to-me 2013 Casita
. The brakes didn't seem to be working when I jacked it up and spun the wheel (the original owner had never used the electric brakes, as he had no controller in his truck). See this thread:
No Current to Brakes on Our New 2013 Casita
The problem was solved by Jack L, who wrote:
Your brakes may be just fine. Let me TRY to explain. When you energize the brake circuit, a magnet "grabs" the drum on the drum face surface. Then the magnet holding onto the drum engages the brake shoes. The forward rotation of the drum is what puts pressure on the shoes. For the brakes to work, the wheels have to be turning. I know you said you spun them, but maybe not enough. If you are getting power to the magnet, hitch the trailer up and drive forward. When moving slowly, you should be able to feel the brakes working as well as hear the noise of the shoes contacting the drum. Hope this explains it and helps.
I hitched the trailer up and went out on some of the quiet suburban roads nearby. Sure enough, going slowly, using the manual 'squeeze' control on the brake controller, I was able to get the brakes to lock the wheels. Then it was just a matter of setting the controller to the level necessary for the brakes to work without locking up or overheating.
For good measure I had a shop go over the brakes and bearings, which turned out to be in good shape (they did repack the bearings). Any good auto mechanic can do this, or you can do it yourself.