There are several ground pins, so I don't believe the damaged pin has anything to do with you problems.
I would run a SMART diagnostic and a surface scan of your drive. Look for reallocated, pending, or uncorrectable sectors. The scan may also show "slow" sectors, ie those that require several retries before they can be read.
HD Sentinel (DOS / Windows / Linux):http://www.hdsentinel.com/
HDDScan for Windows:http://hddscan.com/
See this article for SMART info:http://en.wikipedia.org/wiki/S.M.A.R.T.