I played lots of YouTube vids yesterday in an effort to help me understand what was going on, and went home last night determined to tackle it, as I love the buttonholes made by this buttonholer.
Firstly, I took off the feed dog cover I'd been using, it has been doing the job, but now it isn't. I found that the cover which came with the buttonholer was the right one, I just wasn't fitting it correctly. I also took the needle out, guess what? It was actually bent from catching the feed cover. Needle replaced, time to try it out.
It worked well, but something was still niggling me, the needle is still off centre. So, top of the machine came off, and after a few minutes of hard thinking, I remembered where the adjustment screw was - it's at the back of the machine, and access is through a little hole. It was made a tad more difficult, because I was working from the front, and instinctively turned the screw the wrong way.
Eventually, it was done, and it makes such a difference! The needle is centred, and it moves to the right and left as it should!
Sorted!
Thank you all so much for your helpful suggestions!
Jessie