I sent an email asking about repair of the LC-3 and below is the response. I mailed the cable on Friday so I'm hoping but not counting on it working again:
Hi Rob,
Though (unfortunately) it is likely that your cable is not repairable, we can certainly take a look at it. Just send it to us,
and we'll let you know how things look. Our address is:
Sennheiser Electronic Corp
Attn: Service Department
1 Enterprise Drive
Old Lyme, CT 06371
Thanks for your business!
Best regards,
Service Department
860-434-9190, ext. 2