I think on every 400/4 I have ever owned (all S/H, I could never afford a new one) that adjusting screw has always been bent! They always look ok until you try to adjust them and you then find they wobble in the thread and lock up! They are almost impossible to straighten out. I think the bolt is so thin the thread will seize in the alloy of the fork leg for fun. Make sure you use a bit of copperslip on the thread and lock nut when you assemble it👍