I had a lot like that.The drum centers are stuck to the axle.I usually hit them with a hammer and work them around.I wouldnt doubt that the drums also have a ridge built up toward the backing plates.Makes it almost impossible to get past the shoes even though the drums turn free.Either adjust them down or keep working them off.Ive spent over an hour trying to get drums off some at the shop.Until you get the drums to pop off the axle center you wont do much though.Hit them near the hub center and keep turning them as you hit.Rocky