The brother 8500 does not do free motion. It was one of the problems with this machine from the time it came out. From what I remember it had a special roller that feed thread and the thread couldn't be delivered fast enough for free motion.
Brother corrected the problem in their newer machines , but the Brother 8500 will always have this problem.
I will try to do more research on this if you would like.
Sorry to be the bearer of bad news :cry:
Margaret