Bobbin tension Your answer did not help since it does not list Pfaff 7570.

To access the tension disks, remove the top of the machine as follows: 1. With the carrying handle raised, remove the cover (the piece that has all the stitches pictured). 2. Unscrew 2 screws completely; one is in the depression where the thread spool goes and the other is right behind the bobbin winder. 3. pull straight up. You may have to jiggle it a bit. 4. you should be able to see the tension disks from here.

Check this link, it is threading diagrams, hope it can help you.

Hai. Tension is to tight on your bobbin? If yes, First you change the bobbin case. Because when you stitch is not properly and not finishing.

A good way to set bobbin tension.
Thread bobbin.
Hold bobbin buy the thread.
You should be able to hold the bobbin up buy the "pig tail" thread and the bobbin should not fall to the ground.
You should be able to give it a good shake and it drop about 2-4 inces.
Are you having looping on the underside of the fabric, if so this will not fix this problem.
If that is the case let me know and ill post a exp for how to fix that.
hope this helps

you might try changing the needle
check the thread tension
try using a different bobbin-sometimes they can warp

When you thread your bobbin in the bobbin case, hold it only by the thread. If the bobbin and bobbin case fall, the tension is too loose. If this is the case, turn the bobbin tension screw 1/4 turn until the bobbin and bobbin case do not fall when only holding by the thread. The top tension should be set between 4 and 5. The best way to see which one needs to be adjusted is to do a zigzag. If the thread is pulling more on top and your top tension is set between 4 and 5, the bobbin tension is too loose. If your top tension is set between 4 and 5 and it's pulling on the bottom, the bottom is too tight.

If the thread is looping underneath, you're top tension may be too loose or the thread may not be in the take-up lever. If it's looping on top, double check that the thread is in the bobbin tension or that the bobbin tension isn't too loose.

I have found that either the bobbin is not threaded correctly or the top is not threaded correctly. Try re-threading your machine. I always sew on a test piece before sewing on my project.

Thread tension. Beware of adjusting the bobbin screw. Pfaffs maintain their tensions just fine without adjusting the bobbin tension, unless you're using some crazy thick or fine thread. If you must change your bobbin tension, you would be well-advised to buy an extra bobbin case, because re-calibrating your tensions after changing them can be less than fun.

Increase your top tension, and your looping should cease. I normally keep my tension around 4.5. Also make sure you're using a good quality thread, and that there's nothing in the upper tension assemblies. Sometimes a tiny piece of debris can keep the top tension from applying enough tension, so turning the machine off and blowing some canned air in there can help as well.

Good luck,

-R

Check your bobbin tension also. Embroidery bobbin thread is finer than sewing thread and you may need to make adjustment on the bobbing case by turning the small screw slightly. The type of stabilizer can affect your embroidery. An excellent reference for machine embroidery is Embroidery Machine Essentials by Jeanine Twigg, available on Amazon.