Try calling them up on the phone because on my B&W towers i broke off one of my grill nipples, they sent me a pack of replacement nipples for free. Great customer service by the way. Im not sure about the EMPs but most nipples unscrew because this is a common problem.
Just be very careful if they do unscrew & if you try to tap the broken one out. When i was working on mine, my hand slipped and my tapping bit went right through the grill itself!!...Talk about your heart sinking out your butt!!Otherwise if you cant replace the nipples themselves they most likely will sell you the grill seperate.
Hope you get it figured out, I know it can be a big bummer when new stuff gets messed up even if its very minor.
"The first scratch hurts the most, just dont let it happen again!"