Headphones don't stay in headphone jack

Hello, I've been working on this iMac for a while, and just when I thought everything was working ok, I plugged in a pair of headphones to find that they don't go in all the way. When I push them in, they don't lock in, but kinda get pushed back out. When I hold them in place, no sound comes out and changing the volume just shows the not allowed sign. It seems like the jack was probably pushed in a little, as a similar question noted from a while back. So, is it possible to replace just the audio jacks on this model? And do I need to even replace it, or just move it back in place? Finally, are there any alternatives so I don't have to tear it apart again? Thanks!