Thanks, Tammi. That thread is great for your pictures showing the differences of the 15 and 115. I thought it might be Central Bobbin, but it seems like such a meaningless distinction. Central to the left side of the machine?
This looks like a sweet deal for someone, but would it have been so hard to take a picture of the whole front of the machine? It looks like it's in a storage shed, so it would be harder now.