Thanks for the come-back Mark, but grouped objects are not at the root of the problem. In this model, I've linked successive vertex objects in a heirarchy in the Sequencer, but not grouped them.

In the left pic., the hotpoint is centered. After I created the forearm, I moved the hotpoint up to the elbow pivot point. Later, when I wanted to fine tune, I tried moving it again, and started "the Chase". At this point I can only center it. [CTRL_ALT_H]

In the right pic., I try to move the hotpoint. [Down, in this case...for clarity] It moves 'way to the left, tho' last night the problem was worse, in that it moved farther for less mouse movement. The small red arrow/blue dot shows where my cursor is. ['Print Screen' does not print cursor]

I'm not sure what you mean by "new Assembly Room"? I've only had one since I started this model. All objects are built in the Vertex Modeler. Is it possible to have more than one Assembly Room in a single document? [I suspect this may just be a terminology problem]

What I did do, was to install a cylinder in the Vertex Modeler, then align the way it would be upon completion in the Assembly Room. That way I can toggle back and forth to the Assembly Room to check the progress. Could that have confused the forearm? But why didn't it happen sooner, or on other pieces?

I tried unchecking the "Lock Hotpoint" box. At the bottom of the Properties Tray I selected "Lock Center Only" I can't see that either did any good. It didn't change my hotpoint problem.

Since this model will require 'bones', will that over-ride my problem since the object rotates with the bone, not its own hotpoint? That would be nice, but I'd like to see this one solved on its own. Thanks again.