For the record, the difference between the clip as it exists outside the project (right) and the clip as it exists when imported (left) appears below. Note this is true only of some clips, and the size-change retroactively has been applied to some existing projects that were made with Adobe 9, the version I had before 'upgrading' to 14 in the summer. I cannot zoom in or out or change size (at least, I can't zoom to include the parts of the clip that have not been imported). That version at left is literally the entire clip, once imported into a project:

Two problems:
-one minor glitchy issue that seems to be gone with the reinstall
-the projects and files that were at issue were or used MOD files. It appears from posts around this forum and elsewhere there is a long history with MOD files and Premiere not working together, though they work fine in my old Elements 9. The solution appears to be either editing such projects with an older (but not too old) version of Elements or to use Elements (or various conversion programs) to change MOD files to anything that Elements can read properly..
Of course, given that the problem seems only to apply to really old or more recent versions of Elements, I wonder if it can be addressed by Adobe.