Wish I could Dave.
No doubt you've confirmed the actual coil is open circuit - and already contacted Sennheiser's spares dept. (which I believe is now a separate division?)
They might have an excuse for not still holding spares for that model though - wasn't the 414 first around 56 years ago?
Wouldn't be surprised if somebody makes a pattern part, whether it would be a close enough match is another question.
Thanks, have done both but Sennheiser can’t help because of the age of the headphones. I’m not aware of anyone making a pattern part so even if they had I’m not sure I would trust it.