Sennheiser directly has some in the shop, but according to the shop information they are currently not available.

Unfortunately, I don't know either, I would have to have new ones myself. In addition, the cover underneath the attachment that is attached to the headphones has torn off on my right higher. Do you also have this problem? The headphones still work, but the right side is now a bit louder.

Otherwise, I would check with Sennheiser directly.