I really did not need another sewing machine but, check out the one I picked up at a second hand shop for $12.00.
It has a drop in bobbin and definitely, it needs to be threaded the right way. Everything works and works well, and it came withe the button attachment.

Many extra thread holds, and a little confusing about how to wind the bobbin.....hubby had to tell me how.
My sewing machine has a serial number, is a Singer in a free arm table. I researched the number on the Internet, my machine dates to 1957 and was someones prize, obvious by the way it was taken care of.
I suspect I'll do the same. C & G Design.