1999 9-3 rear brakes locks up in reverse
 

My son's 9-3 hatchback emergency brakes lock up when in reverse stopping the car. Then if you put the car in forward for a few feet then put the car in reverse the car can go 15 to 20 ft and then lockup again. The emergency brake handle does not engage the brakes until the handle is all the way up. I took the car to an empty parking lot and applied the emergency brakes for about 20 seconds to get off any crud on the shoes and it seemed to help for a while but the issue has resurfaced. BTW the emergency brakes work fine while driving forward, they will lock up the rear tires. Got too much snow to think of doing it myself right at this moment. I think this is probably an emergency brake spring broken in the rear hubs but I thought of putting thread this out there for any comments or experiences. Any other ideas or fixes available?