i'm 99% sure the "lamp defective" warning i'm getting in my car is due to the sidemarker bulb sockets. i put in new bulbs and they light up fine, but i still get the warning. the sockets look very dirty and have lots of green/grey crud on them, what can i use to thoroughly clean the sockets?

thanks..

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Current cars:
2001 MB E55 AMG
2003 Honda S2000
2000 Honda CRV

Gone but not forgotten:
2004 BMW 325i 5sp sport
1999 BMW 540i sport
1997 MB E420
1995 BMW M3 coupe