Can't get drive hub out of washing machine to replace gearcase
I'll answer my own question.

I resolved this by


whacking the heck out of the drive hub with a hammer
using "rust buster" penetrating oil in all the cracks
eventually, i had to drill out one of the stuck screws
then finally, I split the center piece in half with a metal chisel


Summary: Brute force removal method. Good thing I had already bought a replacement hub assembly.