I had 2 brackets made up following the drawing from Mr Blustreak and had exactly the same issue on both cars I was fitting them to. It wasn't actually as bad as yours seems to be and I found I needed to lengthen the holes downwards by about 50%. At the time, I assumed that either the drawing was wrong or that my tame toolmaker had made a mistake. Now I'm not so sure...
They still did the trick in stabilising the servo, though.