Sewing Machine Problem

I know, I know -- two blogs in one day -- amazing! Anyway, I wamted to put this problem out there -- I have two friends who have older Pfaff sewing machines -- nice ones with bells and whistles. Well, we recently did a workshop on free motion machine quilting and both these machine siad NO WAY - WE ARE NOT GOING TO DO THAT. The machines got all kinds of thread balls and nests in the bobbin area. My friend Mary Lee's machine hasn't been the same since -- she can't seem to get the balance adjusted once again. Is free motion quilting a problem for older Pfaff machines or are Mary Lee and Sherri doing something worng here? I did ask another firned who had a Pfaff and she doesn't have any problems with it and suggested that maybe Mary Lee and Sherri didn't have the presser foot at the mid level point for free motion....... We'd all be interested in anyone's thoughts or experiences on this subject. My email is: littlequilts@windstream.net Speaking of free motion quilting, here are a few of my recent projects:

What do you think? I particularly love love love the spiral swirls design.