I recently picked up a used dish from a friend. It is elliptical, black with the "DISH HD" logo on the front. It didn't come with an LNB. Since it's a large(r) reflector, I'm thinking of using it in the future to grab 118.7. I have the 500+ LNB on-hand, but it doesn't look like the screw holes are going to line up. The holes on the feed arm are perpendicular to the holes on the LNB (i.e. they don't line up.) I did some reading online, and it seems like these dishes can have different length support arms...? The reflector should be large enough to grab 118, but I can't attach my DP500+ LNB to it. Can someone please help me make some sense of this. What am I missing? Thanks.