You could consider using
Sugru (or any other brand of moldable plastic/glue, not that I know any).
Get it here:
https://sugru.com
I've had great success using Sugru to mend my hopelessly shoddily made Denon AH-NC800 and for securing the USELESSLY loose USB cable on my Lacie HDD:
It's not very pretty but it works like a charm.
Also, while I'm at it, a bit of consumer advice:
If anyone is considering getting noise canceling headphones, steer the hell away from the Denon AH-NC800.
The sound quality and noise cancellation are both excellent but the build quality is just appalling.
Absolutely horrendous.
The ...thing that goes over you head (?) is made purely of brittle plastic and full of weak little joints (also plastic) it
will break.
Worst investment I think I've ever made, worthless for frequent travel.
-unless you fix them with Sugru and some small metal braces, then they're quite alright.