Thread: Pfaff 18.8 using Quilty Artist stitch size changing suddenly

hi
I have an Pfaff 18.8 using Quilty Artist stitch size changing suddenly in middle of an pattern ... HELP

Any ideals whats going it happens every now and than.

I am not familiar with your machine but on my machine a skipped stitch can have many causes. It could be really dense fabric like batik that will sometimes skip a stitch and I change to a sharper needle. It can be something impeding the flow of the thread. Check and clean out the bobbin and thread guides. If it is a computer guided design there may be a glitch in the program?