[Mgs] Clutch master cylinder

[Elliottmg]

Yesterday I started to work on the clutch master cylinder for my project car and ran into a problem.  The car is a 1971 MGB and the cylinder is an unmarked Lockheed (no circles or stripes).  The rebuild kit is Moss 180-965.  The new spring plus the new piston plus the push rod will not fit into the cylinder. It isn't even close -- Probably a half Inch too long with the spring fully compressed. When I looked into the cylinder I can see something rubbery at the bottom end of the cylinder down by the reservoir. Should there be anything rubbery down there?  If not, could an old seal be stuck in the cylinder?  Thanks for your help.
Elliott in Maryland