Hello,
This is my first post. My Pfaff GrandQuilter is skipping big-time on the top of the quilt and breaking threads every 10 inches or so. I have changed out the needle, cleaned the machine, re-threaded the top and the bobbin. Any ideas????

Welcome to the board from Southern California!

Wish I could help, but don't have a Pfaff! Someone here is sure to help! Welcome from Kentucky!

welcome from minnesota and hope you can resolve your skipping issue

You have tried most of the things that usually fix this problem. I did have one time that I had obviously knocked the thread tension knob out of it's place. Check were it is currently set and then tighten it all the way in and all the way out a couple of times and then put it back to it's normal setting. I could tell mine was not right because it didn't feel like it was in place properly, there should be a little play but it should be set square in it's place. You might also try running a slightly thicker piece of thread through it to see if there happens to be some lint or a piece of thread stuck. My bobbin case in also a little tricky to get it to seat properly but usually if that is the problem the case will actually fall out while sewing. Good Luck, hope you find the solution.

Check the hook there could be a burr on the tip.

A couple of things come to mind. Did you try a different bobbin or a different spool of thread. My Grand Quilter sometimes is finicky with the thread (even when it's a brand I've been using all along. Sometimes there is a spool that's just "off" and the machine doesn't like it.) When mine starts breaking thread it's usually tension-related like Lori said. Try "flossing" the tension disks with an index card or a thick piece of thread and see if you can get any lint out of them that way. You might not even see any lint but it could still help. Good luck.

Also, check the needle size. You may need a larger needle for the thread you are using.

You might change the needle again. Sometimes they are mis-manufactured and have a little burr that can cause problems. The repairman who maintains my machines says that about 10 percent of needles are defective. And check to be sure that the needle is inserted correctly and that the needle is inserted all the way. A tiny bit of deviation with the needle can cause some real headaches.
My sympathies with your stitch problem. It can be soooooo frustrating!!!!

Welcome from Ireland. If you go to Search and type in Grand quilter you will find lots of posts.