The older guide RSC's had issues wit out of spec pistons that would make them stick. I got my RSC's replaced recently because of this issue. They are great brakes when they work correctly. I am two months in with the replacement ones and they are excellent. You can call SRAM with the serial number of the brakes and see if they fit the bad batch. They may well replace them, but you have to go through a LBS that is an authorized SRAM dealer.