Binding back brake ...knackered hub?

The rear brake on my 1964 Li150 is binding (grabbing). I would say it's once a revolution of the back wheel. I've cleaned the inside of the hub with emery cloth a couple of times but the problem keeps coming back. The shoes look fine.
Could the hub have gone out of round (slightly oval) somehow?
Otherwise, what's the likely cause.
TIA Chris
Could the hub have gone out of round (slightly oval) somehow?
Otherwise, what's the likely cause.
TIA Chris