Everyone who's tried the Electro-Harmonix 7868s knows that you have to stretch the pins on the original sockets for them to fit. Here's an adaptor that allows the EH7868s with the original sockets.
They're B&K adaptors made for their tube testers - the ones that had only a novar (large 9-pin) socket & not the magnoval (XL 9-pin). Allowed testing magnoval tubes with just the novar socket on the tester. I got two from B&K testers that I bought, one from another AKer and one off ebay.