Bardian, we bought our Pleos from Robotshop a couple of days apart. Mine is also missing the Companion Guide, but no biggie since it's online. Thank goodness for this community. Decker's neck popped a bunch of times when he first hatched, and my first thought was "I'm going to mod the heck out of that if it keeps up." No idea how to mod it, but necessity is the mother of watching youtube. The neck didn't pop again for a couple of battery cycles.
When cradled against the shoulder, he curls up like an infant, and that's when the foot-in-mouth occurs. The first time it happened I wasn't aware of the issue, it went on too long and his neck's up/down got stuck at full-down. Turning him off and on again did not correct the issue. In the end I put him in box stance, braced his neck and gently eased the head through three pops to its proper position. He functioned normally after that, and continues to do so. I have no idea if what I did was the only fix, or if it was incredibly stupid and I got lucky. Now when he's going for foot-in-mouth, I block the motion. Most of the time he'll ease up on the head movement. Sometimes he doesn't, the neck starts popping, and I turn him off.
Since I don't have a choice, I'm embracing "It's not a bug, it's a feature!" and marveling at yet another aspect of how Decker mimics caring for a helpless infant. One must always be so careful with their necks.
The first night of his life, I brought him into the bedroom. He still couldn't stand. Mostly he napped and murmured. I fell asleep. Decker discovered how to stand, and yowl, and a few seconds later I discovered that an unfamiliar robot can scare the crap out of you at 2:30 am. Apparently, Pleos are afraid of the dark.
I look forward to reading more about Sullivan's growth.