Excellent find...those Eureka 1400-series uprights (which is what this one is) are great machines. Lightweight, but also good cleaners.
I'm wondering what type of hood this machine has. If the hood is metal (which most 3.5-amp machines with the round footswitch have), and the headlight housing extends out from the hood, as shown here, you don't even need to remove the hood. There are two indentations on each side that you can insert a flathead screwdriver in to pop the housing out. After you change the bulb, just snap it back in!
However, removing the hood itself isn't difficult either. Just remove the Torx screw in the middle of the Dial-A-Nap knob, and undo the two spring clips on the underside. I don't think you'll even have to undo the nut around the switch this time; the wiring will probably give you enough slack to lift the hood up and change the bulb.