After a year and a half of regular use, the headphone jack in my Samsung Captivate developed a wobble and lost the ability to maintain a stable connection for my headphones. With six months left to go before I can upgrade, I searched online for replacement instructions and found ifixit.com.
The repair went perfectly. I purchased the replacement headphone jack assembly from repairsuniverse.com and followed the photos in the guide. They were spot on.
If you are taking apart the Samsung Captivate, ALSO read through the "motherboard replacement" guide. There are some details in it that aren't necessarily covered explicitly in other guides.