monler

See my guide in comments, it's really easy, and I did you after a year without being able to lower and rise the chair.

I've tried multiple times to pull the gascylinder from the top, bu you can't. Simply hit the metal that connects with the top of the gascylinder 3 times semi hard with a hammer (nylon hammer recommended), and the gascylinder should release from the other part, and you can pull the red cap off and reassemble. THIS IS THE T1 MODEL!