The mechanism to fit the bulbs is not very well designed and it's possible to install the bulb mis-aligned. That's because the bulb fits up against these fanned out prongs that have give. So, make sure you take your time and check it over before and after putting in the new bulb. I happened to mis-align one of my bulbs and locked it in place. This caused the beam pattern to turn into a shallow V shape and for awhile I thought I might have broke something until I went back in to re-install the bulb.