I have a Burris 3 X 9 scope that I've had my model 70 winchester (.270) for years (more years than I can recall). Recently the power adjustment rings (if that's not the right terminology forgive me) have been increasingly stiff. Is there something I can do or is it time to retire the scope? Everything else works fine and I love the scope. I know if I take to a gun smith, they'll charge me $50 bucks just to look at it. I could that money toward a new scope.