Those are used for visiblilty, not illumination, correct? AFAIK we don't have anything like that in the States, and for sure I've never seen a reflector equipped for this function. Assuming that the reflectors are the correct ones for the application, and in good condition, it could be differences in the bulb. Different manufacturers might mount the filament differently, and at different distances from the base, yet sell the bulb as "P/N XXXX". The bulb sockets are seated properly?