My RS GoPro mount broke on its one and only outing in pretty much the same place. It'd be good if RS offered a replacement piece.
I now use this https://gopro.com/en/gb/shop/mounts-accessories/large-tube-mount/AGTLM-001.html which presumbly gives a smaller field of view but is solid and works.
I broke my RS Gopro mount for the boom. The part which is acutally broken is only the plastic bit which slides into the boom and connects to the carbon pipe on the other side. Since RS only lists the complete mount as spare part and that is more than a 100 quid I am looking for just the 8cm of plastic bit. Any ideas where to find this?