Rancilio Silvia screw for front upper panel (switch panel) and back casing.
Although not present on the original Rancilio schematics.
There are Six of these screws on a Rancilio Silvia. Two hold the back casing on the frame (top holes only, bottom by 2 inserted threaded studs). Four hold the front upper panel to the frame.
The same screw is also found on other Rancilio espresso machines.
