Premiere CC: How to select/drag clip in program window?
To answer my own question, I found a solution by clicking around finally. In the Effects Control panel, clicking the Motion property label causes handles to appear on the video in the Program Monitor. Then, with the Selection tool, you can drag the image to reposition it, or drag a corner handle to scale it. I believe I was able to do this in earlier versions without first selecting the Motion label, but at least I can do what I want easily now.