Mine is a 2006 model TW. When I adjust my chain to where it is correct according the the service manual, both sides are in #5 notch. No matter how tight I tighten the axle bolt/nut, when I take it for a ride, the chain side adjuster works it's way to the fully loose position. The right side stays put in the #5 notch. It's the left side that won't stay put. What am I doing wrong?