At the risk of prolonging the discussion. 6-32 Thumbscrew on Amazon appears to be the exact one Elecraft is using. I bought a 4 pack to have spares. From "The Thumb Screw Depot." https://www.amazon.com/gp/product/B09FZNJ52Y/ref=ewc_pr_img_1?smid=A1AFNJJFLAFKUA&th=1 John, N1AU