Thanks for the advice. Is this what you mean and if so, what size do you use? Also, do you not use a magnet but get the sensor very close to the screw?
https://www.ebay.co.uk/itm/115335128825?itmmeta=01HWTSZC5HBBG9E5KA41WW2QMG&hash=item1ada8266f9:g:8bIAAOSwNrViUS56&itmprp=enc%3AAQAJAAAA8AviJmALaN4vosyJ0l6h6QZkNxxXb6GjQW5hoqjCc%2FcbYRHPZrQwTYifuer9%2FHrdd%2B%2BawEG1YrboceTu0wAQzWv7zMyQNpUGV3VplPPLveabPLjqBSJkpAkrpho3NXG9QPqR3vT4MrNjaUTsyc8iMdy1FsJ8Ph5rT4FMyRA6a6AwnC673KpdEk5zT0XZiWfoBp%2BqXi8ACF8Pb0lG0D11WNK9WFzQiEEdRlvF1J3ljgG1VANvhsqq3Uu%2Fnl1d%2FQswy8a%2Fsji80CKp%2BDTwIaL8Rsqne6G6LRJY%2FWDnMSdRK4iOmzJ7WUa2Xe%2BTj9tnIP%2BTLg%3D%3D|tkp%3ABk9SR47D_dnmYw
