hi all, i am wanting help with my heatsink cnc backings, in one of them the o ring that keeps them secured to the slave cylinder seems to be a bit stiff compaed to the other and when i set my brake perfectly to the rim after a ride there will be a gap at the top of the pad to the slave cylinder but the bottom part of the pad will be normal. can you replace the rubber o rings as i think this will solve the problem or am i better off buying some new ones. help much appreciated.