I'm sorry about that tube socket. The quality control is not so good sometimes. They're wrapped in that wax paper stuff when I get them from China and I don't have time to check them all. Every once in a great while, the ceramic gets molded badly and the tube pin holes get covered up, as you stated. I would recommend the tip of a sharp knife such as an X-acto. Ream the hole out by twirling the tip of the knife in the hole. You have to be careful, though, if it's bad enough you could crack the entire top half of the socket. If it's unsuitable, let me know and I'll send you another.
Cheers for the offer, but i think it will be ok. I can still plug a tube in, so I'll just leave as is.