While you wait for answers, we may have found some information which could help you.
Click here for Pfaff Creative 1471Pfaff Creative 1473 Thread stuck in bobbin race?
pfaff creative 2140?
How to replace Creative Touch 1036 Bobbin Case?
where?
Pfaff 1469 Creative - skipping stitches - timing issue?
Can a faulty bobbin hook cause my sewing machine to skip stitches?