External speaker issues with volume increase

Here is a weird one for you. The external speaker on my iPhone 5 began to exhibit a static like crackle when any sound came through it that quickly turned into it not working at all. Read a bunch on this issue online and tried all the recommended fixes to no avail. After much research, I determined that replacing the headphone jack was probably the solution. I have ton's of experience working on small scale electronics, soldering, etc. so after purchasing a new headphone/lightning jack hardware from ifix it and installing it via the helpful guide, success! Speaker worked and I was so happy. But upon moving the volume level up past the 3/4 level, speaker crackles and stops working and won't work again even after system reset and lowering the volume. Take it apart again, make sure all the connections are seated properly, put it back together and speakers work but cut out again if I move past 3/4 level. Any ideas on what could be causing this? Repeated this procedure a total of 3 times with exact same result. I'm careful to use a grounding wrist strap when working on things and am truly baffled.