They are an easy fix as there is no soldering involved , just tear down remove old part and replace with new. Here's a teardown guide to help
[guide|9925]
replacement parts can be found on ebay
http://www.ebay.ca/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xnexis+7+i%2Fo+port.TRS0&_nkw=nexis+7+i%2Fo+port&_sacat=0
Or Amazon
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=nexus+7+i%2Fo+port
Hope this helps