this has been done over and over in the X5 forum and I personally did it myself- just type in tail light fix - you will need to not only sand but do a an easy solder job. takes about 2 hours or less and will fix the problem

__________________
'14 X1 7000 miles

Hasta luego a

'10 X3 3.0 55k miles
'09 335i 55k miles
'08 528i 94k miles
'09 Mini 88k miles
'06 X5 3.0 112k miles
'04 X5 3.0 128k miles
'99 528i 120k miles