It's a surface mount LED, not a bulb. I've never heard of that being the problem. A TRE changes the resistance in the line to make the ECU "think" the bike is in 4th gear all the time, the only unrestricted gear. That will kill the O/D display as the ECU never "knows" the tranny is actually in 6th gear. Other changes in resistance such as the resistor in the gear position sensor for 6th falling out of range or a corroded connection in the wire from the sensor will also kill the O/D indicator.