I got a possible three story stair project in a 100 year old house where I'm to modify several newel posts and raise the railings with new balusters. But before I can proceed, homeowner wants the squeaks and creaks eliminated. My advice to the homeowner the best remedy is to access the risers and treads from underneath. At the moment, the undersides are inaccessible with drywall and T&G wainscot boards in the way. Can I remediate this problem from topside? In many places, the risers are separated (bowed) from the back of the treads. I shot down some screws to pin the treads tighter to the risers underneath but the results are better if not perfect. Homeowner wants perfect as possible without sparing too much expense (You heard that before????). Any help you can provide is appreciated. Thank You.