Why do I only hear audio out of left headphone?

I actually need to pull the end of the connector out of the audio-out port half-way in order to hear sound out of both headphones.I have tried known to work headphones.Sound comes out of both of the laptops speakers.I checked the system preferences and its set for both right and left.So I'm beginning to imagine that its the Logic Board or another internal problem.Any ideas tips or suggestions are greatly appreciated.Thank You For Your Time

UPDATE:I tested switching the slider found in System Prefs/Sound and once I slid it over to the right it dims the sound really low out of both L and R.This is with the connector half-way out.With the connector all the way in it doesn't produce any sound.