1975 Commando front brake MC

My 1975 Commando has been allowed to sit for 8 years. The front MC was re-sleeved by Old Brits. The piston was locked in the cylinder. A gentleman at an old British bike shop was able to remove the piston and told me that the MC would most likely leak if the original piston was reinstalled. I have typical problems of a 79-year-old and would like to put the old piston in. Is there a site that shows a diagram showing how the parts are put together?
Thanks

$pend on a new 13 mm Master cylinder . Andover Norton .

Sleeved master cylinder sellers fooled me twice; I would never use a sleeved MC for anything but a paper weight.

I had two re-sleeved Norton MCs fail. Both were from a well-known supplier of sleeved Norton MCs. One failed overnight in the garage, the second failed a year or two later between stoplights in town - worked perfectly at stoplight #1, no brake/lever went to bar at stoplight #2.

Corvair,
If you are planning on riding this motorcycle at all I would spend the money and get a new MC.Your front brake is something you want to operate properly.
Mike

Best thing I ever done was to upgrade my whole front brake system to modern brakes after many years rebuilding 50+ year old brake after they tried to kill me, spend money as your life is worth it, don't worry about keeping it all original, as I say I rather have reliable modern front brakes that work than an old brake system that will let you down without warning, I had a first warning the second time I got injured, that was the time I replace while recovering, I was lucky at the time it wasn't at highway speed when they failed.

Ashley

My sleeved front brake works really well. I also change the brake fluid on a yearly basis. I think all of us want to stay alive to enjoy our Nortons. If you cannot afford to keep your bike safely repaired, I would sell it.

50+ years with my Norton is well maintained by me and very reliable, but as I say upgrading modern brake system was one of the best upgrades I have done, I brought a RGM MC sleeve kit but decided to upgrade to modern brakes instead and it's not the only great upgrades I have done, but everyone has their own opinion I choose to upgrade fully instead of doing 1/2 a job, and you might not have any troubles going down that road but so many have been unlucky doing so with doing 1/2 a job + at the time I had the money to do upgrades to make my Norton even better and after being a everyday rider for most of my ownership it deserved it.