Need some advice about changing the brake pads on my 03 Maxima. Real easy to get the caliper off but I cannot get the piston pushed back in, even if I open the drain plug for the fluid. Sorry, it's my first time changing out the pads on my '03, not too familiar with these braking systems. Do I have to somehow disengage the e-brake? The e-brake cable is disconnected, also very easy, but still the piston will not go back in, even under pressure with a c-clamp. Any advice?