TOPIC:

The rear brake shoes on my '79 KZ400H project are stuck tight inside the wheel hub! The wheel won't spin at all, even sitting on the bike and rocking it back and forth. I've tried giving it lots of PB Blaster around the seam where the shoe assembly fits into the hub to let that soak in and some gentle prying, but that hub is not releasing its grip. Any ideas...? 

Check the brake arm and shaft where they enter the backing plate, it may be frozen in the "applied" position. If it is stuck, apply lots of PB to the shaft where it passes thru (removing the arm from the shaft will make it easier to access.  Of course you'll have to install the arm on the splines to try it again.)  Let it soak in for a day, then try it.  Heat will also help. You may have to repeat the process several times.  Remember it's had years to get stuck, sometimes it takes days to free up.  Be patient and you will win.  

Scotty

Another possible cause is the glue that holds the friction material to the backing plate. As it ages, it begins to disintegrate and can result in the material coming loose from the shoe and getting wedged between the shoe and drum, effectively locking the drum in place. If pushing the bike backwards does not loosen it, removing the wheel assembly and prying it apart may be the only option. Hopefully, it is just a rusted actuator rod.

Yeah, I think it was a little bit of both; here's the remains after I put the lever back on and gave it a few love taps with a BFH:
   

...and then set about convincing this little beeyotch to let go its grip - that sucker was in there...note the big Vise grips on the lever...blowtorch heat and plenty of PB and colorful invective got it to budge, then turn, then I tapped it out, put a steel brush wheel on it and it cleaned up nice; currently greased up and waiting for new brakes.
   
I have fresh rear brakes on the way. 

Never underestimate the contribution of colorful invective - coming up with new combinations is always satisfying 

Scotty

And the 1st prize goes to TexasKZ for the "delamination" suggestion   In all seriousness you did well to get that apart without destroying anything