looks like rubber side down
see http://www.zdspb.com/tech/ion/maintenance_solenoid.html
see http://www.zdspb.com/tech/ion/maintenance_solenoid.html
courtesy of http://www.zdspb.comTo reassemvble the solenoid, drop the armature back into the housing with the rubber end going in first. Once it's in, reinstall the solenoid head into the top of the housing. Note that the small notch on the bottom of the brass head section must face forward, or else the solenoid won't function (you also won't be able to install the body if this is put on wrong).