Not sure about the upper brake light dimming but they are prone to moisture and failure,i replaced mine myself all for the cost of the unit,think it was about £35:00....
the only part im told that is fidly is getting the old unit out,but i didnt have that problem as mine was hanging out one morning when i woke up.
![signLOL :signLOL:](https://www.mk5golfgti.co.uk/forum/Smileys/newsmileys/signLOL.gif)