I would recommend Jan Wuesten, he sells a lot of surplus Russian and European tube sockets. The stuff you're looking for is mostly VERY difficult to find. I have a big sack of 14-pin Nixie sockets (same size as 9-pin miniature tube, but with 10 pins in a circle and 4 more in the center).www.askjanfirst.com
BTW, the 26 pin sockets were most often used with Beam-X counter tubes.