Just a thought, perhaps even a dumb question..but.... are you sure that the bit is coming out and not the router height adjustment is loose? I have the same router and often I dont quite tighten the clamp hard enough around the body of the router that locks the height adjustment. It seems that the vibration frequency of the router can move the base so that it winds up making it seem as if the bit is being raised. Perhaps that's not the case just thought I'd chime in.