Cable can also seize.
To get at the inner workings of the handbrake drum you will need to remove the front nuts of the rear prop, slotted screw holds the drum on then it should pull off. The shoe adjuster is on the rear of the drum backplate halfway up .
If you disconnect the cable then undo the 4 bolts inside you can remove the whole back plate with the shoes on and clean/grease it up on the bench.