Of course I've never had the luxury working with death adders, but I am familiar with them from being a regular on the venomous forum. I too have never heard of dystocia in them, or really in any live bearing snake. That's not to say that it can't happen as you've clearly found out.
Your troubles begin with trying to find a hot herp vet. I've used oxytocin inclinic with egg-layers with little to no success. It still should be attempted first BUT if unsuccessfull it greatly increases the need for a surgery. This is because the "uterus" is working hard to expel fetus' and will likely rupture if blocked. There are other drugs that may benefit the likeliness of success with oxytocin, but are used on a case by case basis.
It is hard for me to recommend doing anything without the aid of a veterinarian because doing so is illegal in most countries, and unethical as well... yet, hot herps do put you in a corner. I really suggest you search for one first if you don't yet have one. Begin with arav.com; email Dr.Ken Harkewizc (the webmaster and membership head) for suggestions... ask other hot herpers, and zoos... I hope this helps.
If you end up doing stuff yourself, I hope you've read Dr. Mader's new book Reptile Medicine and Surgery... you'll find it on amazon.com. Things to think about before doing anything. Why did this happen. Try to fix the most likely causes... stress, low calcium, low energy, dehydration... physical blockage doesn't allow you much imput on the situation. I would tackle stress and dehydration first, then energy if you can, and while at that, you might as well supplement calcium.
I really hope this helps, even more than I hope you already have a hot herp vet inline.
Be carefull above all else
Good luck!
Ian