I am trying to rebuild my clutch master cylinder on a 1980 Triumph Spitfire. I am having trouble getting it apart. What is the secret to getting the piston out of the case?

I am trying to rebuild my clutch master cylinder on a 1980 Triumph Spitfire. I am having trouble getting it apart. What is the secret to getting the piston out of the case?

I'm assuming that you took the snap ring out. Put a bleeder
nipple where the hydraulic line comes out and put a bicycle
pump on the nipple and use the air to blow the piston out.