Reverse lights blowing fuse
 

When I put my 2005 996 C4S in reverse it blows the 7.5 amp fuse that protects mirror adjustment, seat memory and reverse lights. It came this way when I bought it this past June. I have pulled each rear light and inspected wiring, sockets and bulbs. No defects found other than a couple of center contact springs broken(?) in various sockets. Have ordered a Bentley book but not rcvd., yet. Any ideas out there?
Thanks in advance.

Should have updated this months ago. Turned out to be the broken contact spring sockets shorting to ground when bulb installed. Replace light wiring harnesses in lights. Solved the problem.