Help with Rear brake master cylinder

Hi


Can anyone help me I am trying to repair my rear brake master cylinder I have dismantled it as far as trying to remove the piston from the cylinder. I have about 3/16 of the piston sticking out the plunger end but when I pull it, it refuses to come out....any help would be gratefully accepted

It should just pull out?

the problem has been that the piston has been sticking holding the rear brake on so I checked the calliper and that was ok I found that if I released the bleed nipple the disc would free so I assumed that the pressure was kept on by the master cylinder....having taken it apart I have never seen so much gunge inside a master cylinder of any sort. Question is how hard do I pull,not having taken one of the apart before I was wary of some sort of retaining clip/screw as with the grub screw in the body

If the barrel and piston are badly corroded then you've got nothing to lose by pulling at it. And if you attempt to rebuild it with new seals it could leak if it is corroded internally?

In fact you might as well just buy a new barrel and piston assembly, as they are not that expensive (about £40, or stainless £65), as you don't have to buy the complete master cylinder unit.