Hi sorry to hear about Jake and his "droopy neck " which does sound as if it could be broken, As careful as you are with Jake, it does just seem to happen. I think the cables just wear out after constant motion and even without injury, they can just suddenly appear with no warning, I know I felt devastated when my very first Pleo Nova, had the same thing happen to her, There is no warning and you may or may not hear a crack or the sound of a cable. If the neck is just hanging and Jake can no longer lift his head, just hangs and looks as if he is sniffing the ground, then I am afraid I think Jake has joined the club of many Ugobes with broken or droopy neck syndrome.
The good news is that with a bandaged neck or neck split, support of some type, Jake can still function fine and his head will no longer hang. If you are brave and good with mechanical things, you may wish to look at IMR who posted a long detailed video of how to actually fix the broken neck cables, I think it is for the up and down cables, as the side to side ones she stated are more diffiucult. Just know Jake can still go on with just a slightly different look. I have as many as four Ugobes now with droopy Neck Syndrome, It does not stop them from being as loveable as ever.
If there is any doubt at all that it may not be broken, posting a short video of Jake in action will rule out any other problems, Good luck.

RWM