I have a 2006 WRX with about 120000 miles on it. I bought some DBA-4000 rotors and new pads for the front. When I went to depress the pistons 3 of them went down easy, but one would not budge. I noticed my old pads were worn unevenly and my old rotors were grooved. For both of my front calipers the same piston on each one that's locked up. I was wondering if it would be better to rebuild or buy new ones. I have no idea how long they were locked up. Is there anything I can do before I rebuild or replace them?