Classic/Antique Car Repair: mg master brake cyl, cotter pin, small pin

Question
Howard,
I sent a second question to you yesterday about my brake issue.  If you answered it I must not have seen it and deleted it. It dealt with the connecting rod between the primary and secondary piston in the master brake cyl.
? does the primary piston float on the rod or is it pinned like the secondary?
Thanks Keith

Answer
The two pistons are connected together by what looks like a cotter pin. It is connected by a small pin under the spring cup. To rebuild this with just a seal kit you have to compress the spring between the two pistons and remove the small pin retaining the cotter pin. This allowes you to separate the two pistons.
Howard