Pins in headphone jack pushed inside, is it possible to remove the metal sheath and fix them
You can open it and have a look but the iFixit guide MacBook Pro 15" Retina Display Mid 2012 Headphone Jack Replacement shows this as the ($30) replacement part and it looks to be made of molded plastic.  If yours is too you won't be able to get to the inside.



Alternatively you could get a USB to headphone jack adapter - they start from under $1 on ebay.