The brake cable for the passenger rear is about 3 x longer than the one going to the drivers side. That is the one that gives you the most problems. Free it up by putting penetrating oil down the cable sheath in all spots. You can crawl under the rear of the car and see the external spring coil returns. Have someone tramp on the ebrake pedal and see which one of these spring returns moves. If they move but won't come back, you can pry them with the end of your tire iron to get them back.
Try that a dozen times.
You probably will need a new long cable. If you do, put lots of grease into the cable sheath and move the cables deep, dragging the grease with it. Otherwise, you will be doing this again next year.