I used the mirror to make sure that the tab on the base of the bulb was aligned with the slot on the holder. If it is not, the bulb base will not set flush, and I would think that the clip would be hard get back in place. Also, pay attention to the orientation of the old bulb when you pull it out. That should get you going in the right direction. The drivers side is the easiest. So, if you do it 1st you can get practice for the other side.