Why is it always the easy jobs that go wrong?! My 500 is fitted with taper roller headstock bearings but they are badly worn and notchy so i thought i would replace them.Problem is the lower outer race that is fitted into the frame, it is flush with the inside diameter of the frame, so i can't get anything behind to drive it out. I have tried driving a chisel into the join from the side with no success and a drill wont touch it as its so hard. Any help appreciated, thanks, Mick