Unless you have the TBU unit, that is only the flash led that goes in the barrel. My tamiya Panther flash led gave me problems from day 1.bi finnaly replaced it with a new one from AAF and this one works perfectly every time. They must be very sensitive or you may just have a bad one like it did. for 50.00 bucks it aint a cheap fix, but I dought Tamiya honors the warrenty being it is an electronic part. Contact them and find out. Im curious. All they are really is a capacitor that stores a hich current charge that is released when triggered. Cappacitors can be very finnicky.