I have the Janome 1600P and one of the original Gracie Frames that the new updated carriage will not fit on. I just couldn't stop the machine from skipping stiches and breaking thread (no matter what I did) so I ended up taking the machine off the frame and am using it on the table as a regular sewing machine. I use the frame to pin my quilts... it keeps me from doing it on the floor and it makes for a very even "sandwich" which I can then quilt pucker free. It takes me longer but at least I am quilting, which is more than I was doing before. I just today got an extention table for the machine which will make things even better.
I will post a list of troubleshooting that Janome sent me that might be helpful to you if you run into any trouble.
Don't be discouraged as you get used to the machine. I have 4 friends who have the same set up and they are happy. I am just not as patient I guess.
Carole