XM Antenna loose

Hi all,
I am hoping somebody knows how to tighten the XM antenna (the one above the drivers head). I washed our new Yukon today and I thought the antenna was going to fall off. I can pick it up about 3/16 of an inch and it appears there is one screw/bolt at the rear up thru the roof and the center is the wiring I assume. There was nothing at the front half or else it has dropped out. Now the question does the headliner have to come out to tighten this or does the cover pop off somehow and tighten from above? It is 100 miles to my dealer and if I can do it myself I will. Thanks for any help.
Gene

I had the same problem with my first Yukon, the dealership had to take the headliner down, straighten, and then tighten the bolts holding the antenna down.

Took it in today to have the antenna fixed and they did have to drop the headliner and the xm antenna was broken inside the roof, something about where a clip attaches so they had to order a new antenna so they get to do it all over again!

Yukon went back in today and the antenna was replaced, nice and tight now