Nuts that hold the plastic shroud of a mobility scooter I'm trying to fix are apparently 17/64". Sometimes I can manage to loosen them with a 1/4" nut driver but often the nut driver is just too small. I've also tried 6.5mm nut drivers and they are too small while 7mm is too big. But I can't find 17/64" nut drivers anywhere! Anyone have any idea where I can get one?