I am so sorry that you are having a problem. I think it is a dealer problem. I have a Janome 4800, and have had no problems with it at all. I have had it for quite awhile, and have only had a couple of repairs--one totally my fault. I forgot that the needle threader was down and broke it. The shop where I bought it fixed it for free. The other problem I had was the bobbin winder quit working and that was fixed when I took it in for routine service. That didn't cost anything either. I am wondering if your inexperience sewing is contributing to your problems. Again, I am so sorry that you are having a problem and wish I was near enough to help you with the machine. If there is anything I can do to advise you, send me a pm and I will try.
Sue