If you don't have coloured glass in your taillights it may be wise to check if the colouring hasn't burnt off your bulbs. We don't want to be dazzling people behind us, do we? In the video you can see the indicator bulbs I took out my car, even though they worked fine. I didn't want to be a twunt with rear lights that are too bright and decided that it was probably time to put some new bulbs in. Now my indicators are way gentler on the eyes.