After having trouble with my scope CRT I've come across all sorts of sites for TEK goodies, this place is sold out at present, but you never know it might be worth contacting them, they might be able to source or know someone who can.
153-0559-00 = TO-18 (4 lead) SFE844M2 sets, factory matched and bagged in anti-static bags.
http://www.sphere.bc.ca/test/tek-parts/tekparts6.html
You could join the TEK forum and seek help too.
http://www.tek.com/forum/viewforum.php?f=5
HTH
Good luck
Chris