One earphone has very low volume after soldering it

One of my earphones “Sony - AS410AP Sport Wired In-Ear Headphones” fell apart after I stepped on it. I broke a plastic part but apparently the earphone itself had no damage. I soldered the wires back to the earphone speaker but now it has a very low volume. I’ve soldered it back together about five times already and the volume is super low, I can’t seem to fix it.

Can anyone help with this? Thanks!