Check your fine adjustment for play...when you lock the router it does not lock the fine adjustment. It may be vibrating a bit if there is play.
Try this...when you make your final adjustment with the fine, make it so that it's on the "up stroke", then lock the router...if you go past your final, go back down and come up on it again...
Try this...when you make your final adjustment with the fine, make it so that it's on the "up stroke", then lock the router...if you go past your final, go back down and come up on it again...