Thank you all for your suggestions. I never heard of a hump jumper, that certainly is an apt name. I'll have to look into it. I'm going slow over the humps and trying to push and pull the fabric, and sometimes lift the presser foot up if it's having an especially hard time, but still, it likes to do its own thing. Strange that sometimes it sews through without a problem. I do like the idea of hammering down the seams, I can see how that would help a bit.