If you find poor contact resulted from the loose connection in the MMCX connector of your earphones, here is a short video to show you how to fix it. Just follow the steps to get it started:
1.Find a flat head screwdriver or an alternative with enough strength and thinness
2.Pry the circle on the MMCX connector from the gap to enlarge its diameter gently until it gets back to suitable tightness
Note: Please handle gently with care and not pry too hard.