How to stop blade from coming off bandsaw

I had the blade keep coming off when I bought this second hand, it took me a while but I eventually worked out the problems which I’ll share with you, I also had an electric issue which arose later, I felt comfortable checking this problem as it doesn’t require it to be plugged in so it seemed safe enough, not trying to encourage others to do it, just be aware that buying second hand comes with it risks, and if you have problems definitely get an electrician to fix it for you.