First I'd try some contact cleaner available at Radio Shack then I'd
get a pair of tweezers from http://www.smallparts.com
TWEX-03, about $25.00. Pins 1,2,3 and 5, I believe are used in the ethernet connector. Pull gently with the tweezers to fix the pin with the power off. A hub or switch's indicators can be used for 1st order connectivity. Use another RJ-45 jack to practice on so you can feel the forces necessary.
Depending on the manufacturer, some jacks don't damage easily when the proverbial square peg is inserted into the round hole.
These tweezers are small and are great for getting out splinters.
I've done it a few times by plugging in the wrong cable to the Ethernet jack. The engineers that created USB didn't make sure the USB cables would not fit in.
The Belkin snagless ethernet cable does well for easy to remove and yet protects the plug.
I've also created dummy plugs (crimped with no wire) for Ethernet when I was primarily using the telephone jack. Now my primary connection is wireless.
Now I'm labeling the jacks on the keyboard side. We'll see what that does.