Marion,
Puppy giggles!
Try a Topstitch 90/14 or a Microtex. My LQS likes the microtex. Another LQS says Topstitch 90/14.
Have the dealer check the needle holder. Make sure the needle is tight up to the top. Pushed all the way and screw tightened. The screw can loosen after stitching.
Have the dealer check inside the machine. You can have a burr inside where the thread goes around the tension. They just file it down smooth.
When you change thread always pull out thread from the needle area and not backwards from the thread spool. If the thread is shredded up inside, I carefully use tweezers or one of those dental tools to grab it and remove.
What brand of thread are you using when this happens?
What bobbins are you using? Have them check the bobbin hook as it comes around. It can get damaged or nicked with a needle break.
What fusible are you using? There were some issues with some of the fusible products a few years ago. I like SAS lite, Heat and Bond lite, Misty Fuse and Soft Fuse.
Check the machine preferences for the height of the pressure foot. It should be on the default setting. There may also be a setting for "fabric thickness" on the preference page.
You should not have these issues with your machine. My projects vary in thickness. Sometimes there is two layers of batting plus the other fabrics.