I'm getting a FW for Christmas, but my DH wanted me to sew on it and make sure it worked. He got it on e-bay and the seller offered a 7 day return policy. It was very sluggish and seemed to have difficulty getting going. I oiled her up and she sews like new. I can hardly wait till Saturday!!! I say all this to advise that even if you test it out and it moves slowly probably a little oil will help. Also make sure you get the bobbin case in correctly or it won't sew right. I had to figure it out since when I got it the bobbin case had been removed at some point but it wasn't replaced correctly so that took a few minutes to figure it out.
If it were me and it is the machine you want I'd jump on it.
Marie M.