Tammystitches I have used a Pfaff for 40 years and I will never use Gutermanns thread in my machine. It seems to be the one thread that it won't handle well. As mentioned several times nests on the underside are nearly always the result of the top thread not being threaded through the machine correctly. When this happens always first unthread the machine and rethread, if this doesn't work then try all the other suggestions. BTW I never pull the bobbin thread to the top of the work.