Yeah, I thought that is had succumbed to to dissimilar metals but it’s too clean a cut. I think they drilled a hole and cut a a thing section, and then fitted a shackle with washers to hold it tight. When sails went back on, the riggers didn’t adjust the outhaul so there was too much tension and it’s pulled it right through the slot. I’ve managed to get it all back together and fixed in the groove, so will see what happens on Friday when we head back out sailing. Fingers crossed it holds but you’re right, moving it would be a better idea. One to add to the list to do 
Thanks for all your help
If that failed once it will fail again and probably at the worst time. If you have not seen the movie “Captain Ron”, please do. Its a great movie and Ron’s favorite saying is - “If its going to go wrong, its going to go wrong out there.”