I have one of those on the bench right now (model 534), that's doing the exact same thing. I've drenched it with WD-40 (which usually works), but it still binds in the same spot. The gears are metal, so it's not a broken gear. The last one was the lower blade shaft (right in the front) that was frozen. The previous one was the big, round eccentric that you can see from the open bottom of the machine.
They're an alright machine, but they don't have differential feed, and they can't sew through 4 layers of Jersey knit. I have one at home, but had to buy a Bernina (Juki) so I could sew those 4 layers of stretchy fabric for my home business.
It's worth opening up and trying to find where it's binding.