I recently got Thundertron, and while it's neat to have a space pirate, I wasn't too keen on his limited head movement. Given the groove in the top of the lion head it seems like Hasbro may have intended the beard to drape majestically over the chest. But that pie was too high in the sky and they opted instead to make it handicapped.
The crux of the issue is a bit of transformation assist: a pair of circular grooves act as a track for pegs on the neck joint to ride as you pull the lion's head up and down. I imagine this was to assist transformation but the system doesn't allot the next to rise up to a good level. So by simply snipping the pegs away (cuts circled) the neck joint can go wherever it damn pleases. DANGER! ACHTUNG! NI NI BONG!
This will make the neck joint loose. It can hold the head up by itself but it takes no effort to punch his head down into his chest. It's advisable to hit the joint with some Future or whatever you use to tighten your joints (I needed to do it for Thundertron's lousy hip joints anyway.)