Probably not the 1st, but I’ve experienced an issue with the charging flap, getting it to stay closed after several charges. But I love the EP-B40s and wanted a way to overcome the “open flap”. This isn’t hi-tech nor very pretty, but effective. LOCTITE makes a handy little product called “Fun-Tak”.
The Fun-Tak is scribed/divided into 1.5cm x 0.7cm squares - you’ll only use a tiny fraction of one square. Place the tiniest little amount of the Fun-Tak mounting tab on the open end of the rubber flap (not even enough to touch the micro tip end of the charge cable. (See pic#2). It will last use after use, and keep the flexible flap closed.
Time to go jogging! eMike DuBois