If the anode hasn't ever been removed in 12 years, you may not be able to easily remove it.
I am betting that most of the pros on this site will tell you not to bother trying to patch up a 12-year-old WH.
A good reference site is waterheaterrescue.com .
The site owner has some tips for keeping a new WH going for a LONG time. It involves regular inspections of the anode. He does sell replacement anodes on the site as well.