right earpiece is coming off, is it fixable?

Hi,

I have these Sony WH-1000XM3 headphones that I’ve had for a few years. An undelicate friend managed to break a small plastic piece that holds the whole headphone together (it’s the small crack marked in red in the photos). I “fixed” it with tape since I couldn’t find a replacement part online, but over time the right earcup has become loose. I think the internal cable is coming loose, because the sound in the right ear only works when I hold it in a specific position.

My question is this: taking the headphones apart and re-securing the cable would be possible with my skills, but if the plastic part breaks again, that defeats the purpose. Does anyone have ideas or experience on how to fix this properly and permanently?

Thanks in advance,
Hugo