I agree with Pattiann, you need to have a technician look at your machine. If you look at the Needle Blog you can see the movement of the needle to the bobbin. In your case, it is not completing that process.
While I did not have the same problem, I did have some problems with my bobbins and thought it was my bobbin case. My technician said it was my prewound bobbins which were the wrong size. I should be using the "M" and purchased the "L." The small difference in size caused the bobbin to 'jump' around inside of the bobbin case causing missed stitches. So, when I had it serviced, the bobbin was causing the stitches to be out of timing. Just switching the bobbins helped, but then the timing had to be reset.
And, incidently, the technician noticed that if I were to have held the prewound bobbin like a yo-yo and allowed it to drop, the prewound was so tight that the thread didnot just roll off the bobbin - a really bad sign. Thread should not adhere to itself or the spool. I also feel that this is an issue with metallic threads. I am planning my next blog post on metallic thread and have a hint that may just fix the metallic thread problem for you. Watch for it around the end of February.
A good technician is worth their weight in - well - chocolate. . . . Let us know how you are doing and what the outcome is. Unless your manual says otherwise, oiling is only done by a technician - Pattiann is on target again.
Pat, The Avid Embroiderer
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