I think I had ask this before, I'm having ploblems where it seems as if the flex shaft is slipping in the square hole where it fits into the spindle, could my flex shaft be wore out on one end and need to be turned around and I am curious as to think that the spindle has a harder metal than the flex shaft ?..I have everything working and a new bit but it jerks at certain spots like its grabbing the wood with the bits and it not as smooth as is once was.