There is a special tool to remove the servo cover, but I have fabbed a block of wood and a large screwdriver to depress it while removing the locking ring (trans still in the car). That's the hardest part. Make sure it is clean so no dirt gets in. Remove the pistons(s) and pin. Replace the seals, keeping the "lip" direction the same. Reinstall by pushing in the cover and then put the lock-ring back in place. But first read Bruce's sticky about "strengthing the trans" and set the proper servo band clearance. You may need a longer pin or the adjustable one.