Lost the small spring that tensions the elevation adjustment on the rear sight assembly. I cannot find a spare online. I did find the parts schematic for the pistol on the Diana website but it fails to show that spring. Checked Numrich, PA, airgunspares.com with no luck. The diagrams I find show a micrometer rear sight elevation dial and my pistol has a simple screw. Anyone know where I can get a spare spring, or even a spare rear sight assembly?