I tried the Hehr window screen clips on the SeGi window screens that came with the Era.
The Hehr clips fit with very little modification (narrowed the ends a little) and hold the SeGi screens very tightly in the window openings.
I've ordered all the remaining clips I need from Parkin ($1.23 per clip).
A MUCH better solution than either the original SeGi rubber clips OR bolting the screens to the windows as suggested by SeGi.
No more screen rattles and slips!