How do I exchange the lower Screen?

Press in the Screen, by using the Filling Chamber Tool along the groove of the Filling Chamber. The Screen bulges and detaches from the groove. Clean the screen with isopropyl alcohol or rinsing water or exchange it with a new Screen. Curve the cleaned or new Screen. Insert the Screen into the Filling Chamber with the curved side facing upwards. Press the Screen flat into the provided groove with the aid of the Filling Chamber Tool.