For those interested:
Disassembled head. The silver screw in the bottom is what you have to unscrew with a long flathead screwdriver (or extensions) to take off the handle.
With the exception of the plastic switch and the replaceable plastic inserts on the pump head everything is basically metal (aluminium)
I'm not done yet but I have a brand new one that I want to properly dissasemble and polish (+clear coat) so I'm not putting too much effort into this one.