The shower screen is held in place by the o-ring gasket. You can gently pry at it from various angles with a flat stubby screwdriver or similar implement (I use a demitasse spoon). It takes a bit of patience, but can be done with nary a scratch.

Or, if you don't mind a little extra work, remove the top two Allen screws, lift out the piston, and then push the screen out from the other side. To replace the piston, apply a little lubrication (Dow Corning 111) and ease the v-shaped gaskets past the cylinder opening. I find a dull plastic knife convenient for easing the lip of the gasket over the edge. It's actually easier to do than explain; just remember, if the piston doesn't enter easily into the cylinder, check that leading gasket edge isn't hung up.


From Elektra/Pavoni side by side