Hi. i bought a set of TY250 forks to fit to my TY175. The problem is they don't have the lug on the fork that retains the arm that holds the brake drum in place. I thought the forks were inter-changeable but obviously certain TY250's had different forks.Can any one advise how to get these to fit. If I need a new wheel or drum to match does anyone know what specific TY variation these forks are from. My TY175 is a 1976 american market edition. bought as a non runner and now working fine. these forks are apparently from a 1977 TY 250. I am a complete novice, I'm just getting back into bikes after a very long lay off and hopefully into some trials once bike is sorted and i've got some practice in. I attach some photos and would be very grateful for any help.