I was finally able to find this bad bot a few weeks ago, and I've been tinkering with him ever since. The way I see it, he has two problems. The first is that the mechanism for his T-Rex legs/Robot Arms is unnecessarily restrictive in terms of articulation in both Robot and T-Rex mode. The second is, obviously the HUGE chest gap. There's literally nothing from his neck to his tail. Well, this cannot stand. I've done two things here. The first is I replaced the hinge mechanism with ball joints. They're from an old Technix Lego set, so he has full articulation in both modes. The second is I created a "chest shield" for him using styrene. I haven't added any detail to it or cleaned it up yet, but the general idea is there. It plugs in to the empty holes by the legs, and the screw hole at the base of the tail. Just thought I'd share this for anyone working on the same problems.