Okay, let me try my best to help you out mate,
First of all, I assume:
1) These headphones are 'burnt in' for sufficient time.
2) There are no issues with cables/ sound system/ or the sound tracks.
I have a DIY solution which might solve your issue:
> Disconnect cables, remove the headphone drivers from the yokes,
> Remove the ear pads, unscrew the ear cups,
> You will have access to drivers now: Gently blow air to the backside of drivers...