I've had the roof aligned by BMW already and that's pretty good. The sound I'm getting is not the roof but the deck itself. I have made some progress, but I can't be certain. I note that when the roof tray is locked in position (down) the sound occurs rarely, with the roof tray in the up position for maximum load space in the boot, the sound occurs more often. So I'm now thinking that what I thought was deck noise, is likely something in the boot mechanism that I can hear through the deck. All quite hard to tell when driving or indeed while trying to get in the right position in the car as there's so little room.
I've identified some movement in the roof tray (see image) and I'm wondering if this might be the cause. Can someone else check the pivots on their roof trays and see if they too have this gap?
There is no gap or movement on the left pivot, but there is around 3mm on the right pivot.