How I Fixed Bird-Nesting on my Sewing Machine

Yesterday, I attempted to sew through a thicker-than-normal layer on a tote bag. My machine jammed, though, so I immediately stopped. However, even after I removed the jammed threads, the machine had problems. It was making very large loops on the bottom of the fabric while the top threads were normal. I think this is called bird-nesting in the sewing world.

I went to my user's manual and it said the problem was likely that my top thread was threaded wrong. So, I un-threaded it, re-threaded it, and tried again.

No success.

I went to YouTube and typed in the problem and a plethora of videos came up. I chose a few, and took their suggestions:

I installed a new needle.......no success.
I thoroughly cleaned the machine.......no success.
I removed then reinserted the bobbin.......no success.
I un-threaded and re-threaded the machine about a dozen times.....no success.

I took a break and went to the thrift store with one of my sons.
While there, another son called and we had a great conversation.
I came home, made dinner, ate dinner, watched Jeopardy! and only then went back to my machine.

I turned it off and back on several times.....no success.
I watched a few more YouTube videos......no success.

I decided to remove all plates, the presser foot, the presser foot holder and the bobbin. I left the needle threaded and manually lowered it, watching closely to see how it operated on top of the bobbin case. It got stuck. When I operated the needle faster, I saw that it pulled more thread through, pausing on the sticking point each time, making a large loop.....the same type of loop that had been forming on the bottom stitch.

The bobbin case was crooked.
I adjusted it by about 2mm...and it easily fell into place.
I manually operated the needle again and it glided right through!

Apparently, the jamming dislocated the bobbin case, causing the bird-nesting under my fabric!
Problem solved!

I am a sewing machine mechanic.
I saved a bunch of money by not having to take my machine in for repairs.

Try this idea if you ever have a bird-nesting issue.
I did not find this solution on any resource I searched.

Happy Sewing!
~Tricia