I have a early 2010 unibody MBP 13. When I purchased it I received one of the older white-tipped Magsafe adapters, however, that one melted and I now have a silver-tipped one. Interestingly, the machine only charges when the Magsafe inlet is upside down (wire is facing toward me, alongside the USB/Firewire/SD ports). When I move it right side up (wire facing away), it doesn't charge (not even "not charging" mode). Is my Magsafe port just dirty or something? Can I fix this without going to the Apple Store? (I have a background in computer science and a history of both breaking and fixing expensive computing devices..) I am [2 months] out of warranty and I didn't buy Apple Care.