I bought this for £13.95 (ouch) because I had a credit note to use & it seemed a good idea. There are 3 YouTube vids, which are pretty rubbish, (out of focus, not showing the crucial bits etc).It has a double slot on the left which is supposed to fold the main fabric, but my seams won't feed through it. On the third YouTube video the demonstrator says to fold & press the fabric first. If I was going to do that I'd use the standard foot! What am I missing here? Or shall I take it back?