That's basically it. The overhaul basically fixes it. What happened in that instance was that brake dust got in under the dust seal, and ended up setting like concrete, totally immobilising the piston. Can be done, but might require a bench vice to help hold the calipers while you remove the pistons (when I saw it done, the guy used 2 enormous screwdrivers to lever the pistons out, but just on the bench), and a can of BrakeKleeen or similar. Maybe some very fine (1200) paper to smooth out any little nicks in the pistons. If you are careful, you can re-use the O-rings and seals. Otherwise sus out the brake specialists for a kit.