[HRTKD]

Adjustment could be the issue. It could also be a problem with how the brake shoes are installed. I had a Ford Aerostar van that the dealership royally screwed up. I think they installed the brake shoes backwards which caused the internal brake adjuster (normally activated only when when the brakes were applied driving in reverse) to be activated any time the brakes were applied when going forward. Eventually the brakes would just lock up and the only way to unlock them was to go in with a screwdriver and back off the adjusting start.