Cheers dutch, I’ve had the bolt in and out a few times to see if the crack was expanding or not when fitted, and was pretty gentle on it and the threads seem ok and still gripping fine. Will go a bit gingerly with a longer bolt.
I’m guessing not, since it appears to go right through to the threads. Judging by how I found it, it has been there a reasonable amount of time, and it dosen’t seem to expand or contract when the bolt is inserted or removed. But I’m guessing it’s probably not a good thing to try and ignore. Would the bottom mount take more force than the top one?