I run a Fast Eddie XL and don't get any noise from it.
Sounds like something is loose in there somewhere.
Did you check the MRT ring or whatever it's called?..the ring on the sight housing. I could see that making noise as it's somewhat loose till it's snugged down.
I can usually use the palm of my hand to thump the riser and figure out where the noise is coming from.
Good luck!
