So I received a LEGO pneumatic cylinder from a seller on Bricklink today. I received it in nice working condition. I hooked it up it up to my Lego pneumatic engine. Nothing special or fast just a one cylinder engine powered by two LEGO pumps. After a few hours of playing with it the top inlet stopped working. The bottom one was fine at pushing up while having a bit of force pushing down on it but on the top inlet when you put some upward force on it while its trying to go down it just lets are out from some hole and stays in place. This happened to me one another cylinder I bought before on eBay. The one on eBay also stopped work when I put in on the engine but I guess it had been broken but never noticed. I hope you understood and can answer my question. If you want me to specify something else comment it below.

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    Welcome to LEGO Answers! Your issue if very likely due to one of the internal seals leaking. I've marked this as a duplicate, as that issue has been addressed in another question. Hopefully the answer there helps you out.
    – jncraton
    Jan 21, 2017 at 19:21


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