Cobra Class 3 binding during Reverse stiching

[TrigoLaneTrading]

I searched a variety of ways and couldn't find a thread on this. Sorry if it has been asked and answered somewhere. 

We have a new Cobra class 3 sewing machine and when we go to backtack/reverse stitch the threads get bound up and locks the machine. When stitching in the forward direction everything seems to be working flawlessly. I read online it could be a tension issue, but after a lot of adjusting we seem to have the tension set appropriately so that the bobin thread doesn't show on the top side.

Any assistance would be greatly appreciated.

[Wizcrafts]

@TrigoLaneTrading

Since you bought the Cobra machine new, you are entitled to free support from the parent company: Leather Machine Company, in California. Their contact info is on the bottom of the home page.

Until you are able to contact them and open a troubleshooting ticket, here are some tips for you to follow.

• Make absolutely certain that you have threaded the machine exactly as shown in the user guide that accompanied your machine. I recommend inserting the top thread through the top hole in the top mounted guide post, then turn it around counterclockwise and feed it through the bottom hole to the loop under the top tension disks. This can counteract any right twist in the thread that can cause the thread loop to dissolve prematurely in reverse.
• Make sure that the top thread is fully seated in the top tension disks and that it moves freely when you lift the feet, then tightens when you drop the feet.
• Make sure the top thread feeds through the loop in the check spring and that the spring moves up with the take-up lever and stops moving down as the tip of the needle meets the top of the feed dog hole.
• Make sure that the needle is aligned so that the scarf above the eye faces due right and the ribbed side faces due left.
• Make sure the needle is fully seated up in its mounting hole and tightened in.
• Make sure that the bobbin thread feeds smoothly without any jerkiness or binding and that it has good tension on it. These machines don't like operating with light  spring tensions.
• There are two spring loaded screws that secure the shuttle assembly to the head. Screw them all the way in, then back off each screw 1/2 turn. This lets the thread push the shuttle outward to avoid binding as it goes around the shuttle.The springs over the screws push it back in after the thread finishes its cycle.
• Add some more top tension via the large hollow screw on top of the head, where the presser foot bar moves up and down. If the tension is too light for the material and thread, the work can lift with the needle, causing skipped stitches and mangled top thread.

If none of these steps fix the problem, your hook timing or position may need adjusting. Try to get LMC to walk you through the process. They have videos about this on the website. Do NOT try this without a visual guide or expert assistance the first time you need to adjust it. If you get it wrong, the machine may not sew in either direction. Once you understand the process, you can adjust it any time the timing goes out. Your timing can be knocked out if the screws on the hook, or its driving cam on the bottom shaft are loose. It can also be knocked out it the needle hits metal and the needle bar screws aren't really tight where they connect to a driving crank shaft inside the head.

[TomE]

Thanks, @Wizcrafts!  As always I learned a few new things from your post, particularly about the spring-loaded screws on the shuttle race.  I appreciate knowing WHY as well as HOW.