All kidding aside, I've experienced tight nuts myself. (tuning) I had a rod actually snap at the threads once. If it is very tight and not showing any signs of loosening, I would try to get a small pair of vise grips as close to that end of the rod before you start torquing it much!
Best lyric in a country song: "...One more, Moon..."
Never worked on, Or seen a Dekley.
If it is easy to remove the pull rod from the bell crank, Clip, Hitch pin or Set screw.
So tuning nut can be pulled out away from the guitar, A few inches. Vise grips and hair dryer heat may make the nylon tuner come loose.
Clean threads with wire brush or die.
A rub of bees or candle wax helps to lubricate the threads.
Good Luck on project, Happy Steelin.