Some nodes not present in node resource list


I am trying to add some serial interfaces on a Cisco 7206 router to the Node Details page. When I list the resources for the node so that I can select the interfaces to be viewed in the Web Console, they are not there. I tried un-managing then re-managing the node but it did not make a difference. I believe if I rediscover the node, I would loose my statistical information which I have to avoid at all costs as this is a core node. Any suggestions on how I should proceed?