How does one back off the pistons in the rear caliper enough to make it easy to remove the caliper. I just replaced pads and had the usual hard time trying to wiggle the caliper just right to get it off. I had to turn one of the pistons (the one with the cross slot) to get it to fully retract. Of course, one cannot do that unless it's removed. What's the trick? Is it completely backing off the parking brake adjuster? The diagram of the caliper looks like it acts on the piston with the cross slot.