I'm assuming that you can get the caliper off of the car and take it to the bench.[/ATTACH]
I removed the piston by forcing it out while it was still on the car by pressing the brake pedal with the pads out. I believe you can use compressed air instead. Remove the dust cover if it didn't come out with the pads. It just pulls off. remove the grommets for the caliper bolts, and the square section seal inside the caliper.
Clean everything especially the groove that the square section seal sits in. I also painted the caliper with dregs from rattle cans. Grease the grommets and push in. 
Lubricate the seal with brake fluid and fit in the groove. Fit the dust cover to the new piston 
and lubricate with brake fluid. Push into the caliper, making sure that the dust seal seats all the way round.
[/ATTACH].Fit finished caliper to car and bleed brakes.
I removed the piston by forcing it out while it was still on the car by pressing the brake pedal with the pads out. I believe you can use compressed air instead. Remove the dust cover if it didn't come out with the pads. It just pulls off. remove the grommets for the caliper bolts, and the square section seal inside the caliper.
Clean everything especially the groove that the square section seal sits in. I also painted the caliper with dregs from rattle cans. Grease the grommets and push in. Lubricate the seal with brake fluid and fit in the groove. Fit the dust cover to the new piston and lubricate with brake fluid. Push into the caliper, making sure that the dust seal seats all the way round.[/ATTACH].Fit finished caliper to car and bleed brakes.
