Friends don't let friends lend someone their headphone adapter. Ever.
If your adapter has been 'borrowed', then you need to find some new friends. Right after you've grabbed yourself a replacement.
543684 is a genuine Sennheiser spare part.
It is a 3.5mm screw type socket to 6.35mm jack plug.
Suits a whole host of headphones, including:
Need a different spare part for your headphones?
We stock only genuine Sennheiser spare parts.