so i got a 2015 tom dugan signature complete. Everything thing is awesome except the bars keep slipping. Sanded the bars and stem where they meet, still slipped. took the paint off the knurls and used a utility knife to make x's in the stem and used some foil, and tightened them all the way, and they still slip. Any suggestions? Its redic to think that when i had my sunday freeze stem, bars never slipped.