i've had this pair of Sony MDR-7506's kicking around forever with the right headphone broken so i pulled the apart the other day.
I was able to confirm continuity from the headphone jack to the tip of the red wire, and from the headphone jack to the tip of the orange wire, so it seems like everything going through the left headphone to the right seems to be still connected okay.
I wasn't able to get continuity from the red wire to the orange wire though, and I'm not sure if that basically confirms the driver is busted, or if maybe the wire-to-driver-contact is messed up and I'd need to desolder it and test directly on the contacts.
anyone got any suggestions before i bust out the soldering iron?