Volvo Repair: Brake repair, volvo 240dl, rubber seal

Question
My son decided to blow through the brake pads on my 1989 Volvo 240DL Wagon and right into the metal base.  Metal to Metal contact ate away about 1/2 the rotor on the inside.  In installing new pads and rotor, I was unable to depress the pistons on the inside and assume they were extended too far.  The outer calipers moved back freely.  Is it possible to get the extended inside pistons back in working condition without professional help or overhauling the caliper?  This is a Girling caliper.

Answer
Hi Joe,
        Rear calipers are simple work...if a piston refuses to return into its bore ...chances are that you have rust or glerp in the bore preventing it's return.
    Have someone press the brake while pad is IN outside piston..this will force back piston to move toward rotor...with foot OFF the brake pedal install small rubber or plastic tube onto caliper bleeder..put other end into clear plastic bottle...Loveingly loosen bleeder and push piston into caliper bore...note color of brake fluid and if piston dosen't return EASILY...time for new caliper.
if you so choose...rebuilding that caliper is very easy..usually if you remove rubber seal INSIDE bore cleanit well and sand bore with 280 sandpaper..particuly the outside of the bore under the rubber outer cover...add light coat of light grease to piston..reassemble and bleed...good for another 100,000 miles...be sure piston moves freely
               Good luck,
               Bilbo

           You may contact me further.