i didn't read all the posts, so bear with me
you don't need to crack any lines loose. The knob is how you bleed it.
now, where'd ya crack the lines loose? At the injector (cylinder head) or at the pump? If at the pump, you've likely turned the delivery valve while trying to loosen or tighten the line, which at that point the pump has to come out and be sent in for repair. It cannot turn at all. not even a tiny bit.
and another little tidbit which is irrevelant at this point, but I'm gonna say it anyway. When changing the fuel filter, you don't have to bleed the system after changing it (on this style filter anyway). Turn the valve off on the filter housing. Then remove the filter ring, change the filter, clean out the bowl. Now reinstall the ring nut, bowl and o-ring, with the new filter inside the bowl. BUT don't tighten the ring nut all the way. Now turn the valve on and let the bowl fill up. As it fills, diesel will start to leak around the ring nut. You will see fuel and air coming out. Let it run out until the bubbles subside, then tighten up the ring nut without turning the valve off. You're done. Start the engine and go on about your business.