Are there any tricks to inserting the m-card into the XL4? I don't recall any problem inserting our older XL2's m-card, but with this XL4 it seems like the new-to-us Comcast m-card just doesn't want to fit. The slot seems to be wide enough, about 1/8in on both sides of the card. The slot has 4 little metal "tabs" or "guides" visible on the back which move when pressed. Comcast tech support says they only have 1 kind of m-card. I hesitate using much more force than we've already tried. Don't want to remove XL2 card to compare them, as that would probably require re-pairing.