Inside the upper Piston is a pipe which can be turned a bit and then pulled out. Carefully. At both ends are black sealings. Please note the orientation of that piece !
Inside this Coffee-Pipe at the lower end is the Crema-Valve. This Valve makes the pressure in the coffee-fluid; that makes the good Taste and Crema from the etheric oils of the coffee-beans because the Coffee is squeezed through this valve. Thats the secret why a Jura coffee tastes great. :)
The Crema-Valve Nozzle has a spring and a rubber lid. Both can easy pulled away.
On the other side of the piston is the coffee strainer. It's hold in place by a PH2 screw. When the screw is turned out the metal strainer can pushed off.