I have several Mid 2012 Magsafe i/o boards and cables.
None of them have a missing pin like yours pictured.
If the moisture sensor on the underside of the flat cable still white or is it now red?
Sorry about the poor pictures, low light and cell phone camera
To be on the safe side it may be best to purchase both the cable and board.
Many times on ebay that is the most cost effective way, then you are covered.
If it turns out you don't need the board, you will always be able to sell it.