3-way sockets have the extra contact (in this case it's aluminum in color). This allows a 3-way bulb to be switched 50-100-150 watt.
First the socket shell is removed from the socket cap.
The old socket interior is a quick connect type that has piercing tongs and do not require the wire to be striped. The replacement interior has screw terminals, so the wire is clipped.
Cord slack is fed from the bottom so the wire can be reconnected to the new socket interior.
The lamp cord is split, stripped, tipped and a UL knot is tied in the cord.
The socket interior is attached with the ribbed wire going on the nickel screw terminal and the smooth wire going on the brass screw terminal.
The cord slack is pulled back through the base of the lamp.
The socket shell gets snapped into the socket cap. Tip: Notice the orientation of the turn knob on the socket: in the middle of the harp base. If you are reaching under a shade to turn off the lamp, it is easier to find the turn knob if it is center of the harp base.
Perfect. Total Cost <$3.00 Total Time < 10 minutes.