I'd say the jack might be messed up. I have an issue with my computer with front jack since I have used the same computer case since 2004 and it acts up occasionally giving me only one ear and not both. I am going to have to replace the front audio jack on my desktop computer to fix this. There have been a couple times that I got up forgetting i had headset on and it got tugged to the side, so working for last 13 years with heavy use and a few accidental tugs is pretty good.
Audio on my headset is usually set to the maximum too which is like 70% loudness from what I would expect for 100%. An easy fix would be to make use of an available USB port to insert a sound card stick into there and use that audio, or get a male/female extension cable and use the rear audio jack to get stereo back to both ears vs mono to one ear. I have also seen people replace computer cases to solve this. Otherwise if your good with reworking electronics, replace the audio jack unsoldering the old one and adding new.
