If you have problems finding a resistor, you might want to consider some Redneck Engineering. Find a 1/2 W (or larger) potentiometer, adjust to 4.7 ohms (with a good ohmmeter or by trial and error), then lock in the setting with some fingernail polish or similar. Not the best solution but sometimes ya gotta do what ya gotta do.
Edit: You might have better luck finding a relatively high wattage resistor in a "chassis mount" package. 4.7 ohms is the important part; can't have too many watts. Grab a 100W resistor if you can get it cheap.
