SRAM HydroR Service Manual page 7

5 Repeat steps 2-4 several times.
If one piston is moving and the other piston remains stuck, then
remove the brake pads and use a plastic tire lever to hold back the
piston that is moving. Squeeze the brake lever until the stuck piston
begins to move. Repeat holding back one piston while squeezing the
brake lever until each piston moves smoothly. One piston may always
advance more than the other; this is okay. Sometimes an audible 'pop'
can be heard when a stuck piston is freed; this is okay.
6 Reinstall the brake pads, if removed. Install the wheel according to the
manufacturer's instructions.
7 Squeeze the brake lever several times to position the brake pads to
the proper distance from the rotor.
Center the caliper on the rotor, if necessary.
8 Spin the wheel and check the brake function. The pistons should move
freely and there should not be excessive brake lever throw.
9 If there is no improvement in the brake function, proceed to
Caliper Service.
Tire lever
Disc Brake Pad Advancement Procedure
Tire lever
7