rear drum brake dragging at a particular spot in the roation.

My 1999 Corolla has been making a noise in the rear left wheel like something is dragging or catching at a certain point in each rotation (this has only recently become loud enough to really notice it, but looking at the tire, it has worn a massive bald spot [probably explaining the increase in sound]).

I took the wheel off, and spinning the drum with my hand, I could clearly feel it sticking near the top of the front shoe, then releasing for a normal spin, then sticking at that point again, etc. The shoes were clearly worn unevenly (more wear right where I expected based on the feel), and the front of the wheel cylinder was leaking ever so slightly. I went ahead and replaced the wheel cylinder and shoes all around (even though they were fine other than the wear spot on the left), and had the drums machined.

Unfortunately, this did not fix the problem. I can still feel it catching when I rotate it by hand. If I switch drums between sides, I still feel it on the left, but not the right, so it's not the drum itself. Also, it spins freely if I spin just the hub without the drum on, so it's definitely the brakes, not the bearing that's catching. Also, after driving it a bit, the new shoes already show a weird wear pattern, where the top of the front shoe (where it sticks) is visibly worn more than anywhere else (I know that's fairly normal) but the wear is not even across the shoe (outer to inner). Instead, the outer edge is more worn, making a triangular wear pattern (top and outside worn). That pattern only exists for the left side (the right side looks like normal symmetrical wear).

I'm really stumped. If the shoes were misaligned or the backing plate was bent or something, I'd expect constant drag, not drag at one spot of each rotation, and if the back end was out of alignment, the whole break system should by tilted, resulting in tire wear, but not brake drag at one point. The only thing that makes any sense to me at all is if the shaft coming out of the bearing is somehow slightly bent (resulting in the drum spinning slightly off center such that it only hits the shoes at one point in the rotation). That would also explain the triangular wear pattern, but is that even possible? I'm far from being an experience mechanic, but I've never heard of a bearing failing like that.

Thanks for the help