While I changed my rear pad on my RT SE5, I found that my inside pad had worn to the metal and scratched up the rotor. Can I re-surface the rotor? What is the min thickness of the rotor? Also when I installed the new EBC pads, I could not press the piston back far enough. Is the piston suppose to press flush with the casing? I had already taken out the parking brake assembly and rotated the spine counter clockwise. The piston is still sticking out about 1/4" out from the casing.