The whole of the Copper mine system is moving around (aka collapsing) one bit at a time. There was a sizeable movement in the vicinity of the Blue Rock Chamber earlier this year. That has made a dangerous part of the “thru route” even more dangerous. To get through you had to negotiate lots of hanging death. It wasn’t completely blocked last time I was there in February, but it could well block at anytime. I haven’t been in since February (for obvious reasons) so quite possibly other things will have moved around in that time.