Hi Dave, Check out the bedding of the back rail. I had an S&S D that changed seasonally until I found that the back rail would float off the bed then return. I shimmed the back rail until I had a tight but non binding fit between the back rail and the dags (dogs, hooks, raising preventers) at each location. That worked perfectly, no changes and absolute consistent dip the year around. Newton
This PTG archive page provided courtesy of Moy Piano Service, LLC