Industrial Singer 660 A3 straight sewer. I bought this machine several years ago from someone who used it for sailmaking. It was working beautifully but now it is not sewing effectively, we can't get the tension right. I'm not a machine expert so don't know what it needs to fix it. As is, where is. Buyer must collect. Contact and payment must be made within 3 days of auction end, or item will be relisted.