The hinge on our Maytag 3000 series front loader washer broke. We ordered a replacement hinge. Hinge arrived and replacement was easy except one of the screws would not tighten. It appears that the hole in the hinge is not threaded. Rather than wait for another hinge, we would like to use a tap and create a thread for the screw. Our problem: we can't choose a tap unless we know the size of the screw. Maytag help line said it is a 7-18 3/4. Is a number 7 screw American or metric? What diameter is a 7? Thanks!