I have a XLC Seatpost Clamp for my Haibike Xduro Nduro that I've stripped the hex bolt socket. Anyone know what bolt size I need to replace? If not, what size clamp should I be purchasing 31.6 or 31.8? The label on the clap seems to indicate 34.6 - 35mm, but I know that my seatpost is 31.6mm in diameter. Thanks in advance.