Originally Posted by MyWifeMadeME
He sold you something that doesn't work correctly. Call him back and gently describe whats going on and explain your desires and position. Keep in mind ... you catch more flies with honey than with vinegar.
I agree with this approach. Unless you have totally made up your mind to try to get out of this deal, maybe just describe the problem and ask to bring the machine in for him to show you how it performs for someone with experience on it - from the standpoint that it's just not working right for you, even though by now you may be convinced it's the machine that's messing up. If it does the same thing for him, you've already got your foot in the door as far as demanding that the problem either be rectified at no cost to you or a full refund be given.
Before you go, read the fine print on the bill of sale to know if you signed something agreeing to "as is".
Any reputable dealer will understand that it's much better to send a customer away happy, especially knowing you have a huge audience of sewing/quilting enthusiasts eager to learn about quality machines and reliable dealers. Maybe it wouldn't hurt to mention - in a friendly way - that your many Internet friends are anxious to hear what the problem was.