Speaking of magnets... when we first acquired our 18' flatbed, the wiring and brakes were in dismal shape. I used it for a few years before I decided to rebuild the brakes & wiring prior to hauling a heavy load (a '57 chevy 2dr post from Boise to the Portland area); it had brakes on the front axle but none on the rear.
One puck was worn completely through to the windings and the other one was not far behind. I replaced the pucks and shoes, then repacked the wheel bearings & installed new seals. What a difference! I'll never run a medium trailer w/o brakes again. We also have a couple light trailers w/o brakes & we do fine with those.