I have a Janome 6500 and have never had a problem with any thread type. I have used it all including Connecting Threads, Coats and Clark, Mettler, Aurafil, Hemingworth, etc. I use polyester, cotton and rayon. I do not have any Gutterman so I can't speak directly to that, but I know other people use it without any problem. I do use the Janome brand bobbins made specifically for my machine. This could be the cause if you are using other types of bobbins.