This ought to illustrate better what I THINK should be the correct order for the cylinder.
Missing on the left is the plastic "t" plug, then the spring, then the cylinder, then the flat washer.
Then the rubber gasket with the flange to the right and the cupped washer fitted over the rubber gasket.
The cupped washer has an enlarged edge that points to the right.
This can then be pressed into the housing and then prevents the whole assembly from popping out due to the spring and/or hydraulic pressure.?