Possibly Shorted Out Saber

Reading through this thread I think I'm understanding that you are replacing a single red LED with a tri-LED. Sticking with that assumption because you have a tripple lens on there and looking at the fact that you only have one positive wire and one negative coming from the star I am guessing you wired the 3 LEDs in series. If that is the case those 4 AAA cells are not enough for it. Commonly red LEDs have a forward voltage of around just over 2 volts when they are wired in series that adds up to over 6 volts. Four standard AAA cells give you 1.5*4 = 6volts. 4 rechargeable cells give you 1.2*4=4.8 volts. If you wire them in parallel instead you will get a better result and be closer to needing that resistor. I can't tell you which resistor you would really need without knowing the correct forward voltage of the LED. The ones you have would probably serve you fine without the resistor if you leave them in series. When using that particular lens in an Ultrasabers LED housing I cut wire notches in the side of a penny and insert it between the screw in heat sink and the LED star to get the lens a nice fit while still retaining heat isipation from the LED.