The screws I got are slightly too long to go through the frame and stop before the end of the threaded insert. So you screw the screw in as far as it will go, and it doesn't hold the frame tightly against the screw hole.
(And the hole in the plastic already wasn't quite deep enough for the insert to be pushed down far enough to be flush, by a half millimeter or so.)
Consequently the ... how you say, boss, in the screw-hole, needs to be deeper.
The screws I got are slightly too long to go through the frame and stop before the end of the threaded insert. So you screw the screw in as far as it will go, and it doesn't hold the frame tightly against the screw hole.
(And the hole in the plastic already wasn't quite deep enough for the insert to be pushed down far enough to be flush, by a half millimeter or so.)
Consequently the ... how you say, boss, in the screw-hole, needs to be deeper.