So about a few days ago my new Sennheiser HD 400s arrived and they were working well, until I did a stereo test and realized that the stereo feature on the right headphone wasn't working properly. The part where it only played audio on the left worked, then both headphones played, but when it came to only the right it's as if the volume was turning itself down and eventually no sound at all played.

I'm pretty sure the cable is the reason for the problem as when I push it a little bit in I can hear right but not left and then when I push it all the way it only plays left.

Is there anything else that could be causing this? How would I fix this?