Rear brake adjustment

I have a '92 Metro hatchback. The front brake pads have been replaced 3 times, but the rear still have over 50% life left. It seems that the front are performing most, if not all of the stopping action. Is there any method of externally adjusting the rear brakes tighter than the self adjusters are allowing? Chiltons says the rear brakes are self adjusting.

If I ratchet up the parking brake a few notches, the stopping action is far improved, the front end does not dip as much. I feel the rear shoes are too far from the drums, but that's where the self adjusters set them.

Is there a procedure for getting the self adjusters to function better?
Thanks,

clean and lube the adjusters. im pretty sure they are stuck