have u tried at all to remove the drum??? if u can or will, lift up the rear end so that both tires r in the air and take off the right rear and get a can of wd40 or some kind of lube and spray it into the drum from the brake adjuster hole on the bottom of the inside of the rear drums where the leaf springs and u-bolts are located see if it'll give when someone else spins it you can always buy brake cleaner to clean up the brakes and drum after u get them off soaked in wd40
p.s. FIRST look for a replacement spring setup at oriellys or ur fav. auto part store make sure they have both