My father in law bought a black powder rifle the other day. When he went to adjust the scope on it he realized had no way to turn the knob. The out side ring which tells the increments in which the scope adjusts, spins freely. the inside ring how ever had no notch or knob. Instead it had two holes, both holes had been tapped. Does any one know what tool he needs or is something missing. He dont want to stick something in them then turn in fear of ruining the threads.