Usually, just a larger screw like you already added takes care of the front cover. If it's still loose, install a fold over nut on each side of the rear part of the box. Then install the front part and use new screws that are designed to fit the fold over nuts. You don't want to put rubber bumpers in, because if you're using the 3 position switch yet, the box needs to be grounded correctly for the 3 position Headlight/Charging switch to ground. You also can run an aux. ground wire off the switch to the Battery Pos ground to make sure the switch is grounded correctly if still using the 6V system.  HTH

Steve@B&B

Thanks, I previously added an extra ground wire directly to the switch to ensure it's always grounded.  I will consider a clip-on nut.  I happen to have a large assortment already :)  That might also allow me to tighten it a little more without fear of stripping.