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is your adjuster arm bent?my understanding is that the brakes adjust every time you back up.
I'd remove the wheel cylinder (not the caliper, drums don't have calipers) completely and rebuild it. Ensure the rubber plungers on each side slide smoothly and the spring is in place b/w the two rubber ends. Sounds like the wheel cylinder is not releasing the pressure. then put back in place. I usually hit both sides of the shoes after all is in place to ensure the shoes move left and right, telling me the shoes aren't binding anywhere and can freely move. Ensure the right shoe is on the front and back...they are different sizes. Ensure springs are keeping correct tension on the shoes and adjuster. Ensure adjuster turns both ways easily. Spray WD40 in the adjuster end and threads.Bleed and rebleed the fluid.