You didn't mention what NH model, but on the Class III Boomers, the grill openings are as small as a screen and the "gunk' builds up on them instead of getting inside because all the holes are sealed with rubber or foam. When the grill gets dirty, you just stop, wipe off the crud, and continue. /forums/images/graemlins/smile.gif /forums/images/graemlins/grin.gif