Originally Posted by QuiltMania
My machine (1970s Montgomery Ward) has been having a problem for the past couple of days and I'm trying to figure out what the problem area is so I can attempt to solve it before taking the machine in for servicing.
It sews fine for a while but then tiny loops appear on the bobbin side of the seam. They aren't very big but they allow me to pull the bobbin thread right out of the seam with no resistance.
I thought that maybe I was somehow losing tension as I sewed but adjusting the tension doesn't seem to make a difference. Any help would be greatly appreciated.
This is not likely to be a bobbin problem. The rule is if the problem appears on the bottom side of the fabric then the top thread path is the problem. If the problem is on the top side of the fabric then the problem is on the bottom thread path.
Since your problem is appearing on the bottom side of the fabric then it's your top thread path that is having a problem. My guess is the tension discs need flossed out so the thread seats inbetween the discs properly.