Here is my engine bay cleaning in progress:

And I would love it if anyone could chime in on these pictures:
When I took this apart, one of the little rings fell off, but I noticed that a sleeve is missing (the only piece of that I have is the round, smooth metal piece). Is there a way it can be replaced or should I buy a new one?
Does the mastercylinder look right? I think for some reason I broke it. Thanks for your help!

And I would love it if anyone could chime in on these pictures:
When I took this apart, one of the little rings fell off, but I noticed that a sleeve is missing (the only piece of that I have is the round, smooth metal piece). Is there a way it can be replaced or should I buy a new one?
Does the mastercylinder look right? I think for some reason I broke it. Thanks for your help!