Perhaps you can pull the T-Nut to drive it into the wood. Here's a possible solution:Get a very long screw with the same threads and replace the one you have in there now. Then, rather than drive the screw all the way down, simply use it as a sort of handle to pull the T-Nut into the wood. Once you've pulled it into the wood a little bit, reinsert your standard screw and tighten it down.
Just a thought.