Looks like that particular model is out of stock. I puchased WHL-700R, which is the only other one available.
I am guessing the drum for the rear break is the same thing. I am attaching these two photos to confirm what you posted is accurate as this is an old model, just in case that makes a difference.
To unthread each side (sprocket and braje drum) I pull counterclockwise or vice versa?
Both the chain sprocket and brake drum unthread from the wheel hub in the counterclockwise direction.
Both of those parts can be difficult to remove from the wheel though because they get threaded on tighter and tighter every time that the scooter is used.
Some repair shops place an old pair of bicycle or scooter forks in a large vise and use the forks to hold the wheel steady while the sprocket and brake drum are being unthreaded.
If either of these parts are seized onto the wheel and can not be removed then they are both still available so they could be replaced with new parts.
This reply comes a year later (because that is when I replaced the band break) just in case anyone has a similar thing, even if the scooter is different.
The idea of using an old fork (which I didn't have) gave another one that worked perfect for the band brake part: Put two long big bolts through the two holes you see in the photo,. then clamp both to a table vice and spin it. No sweat.
For the sprocket, I used heat but this method probably would have worked as well.
The rim on my rear Tsunami is coming undone, I need a new rear wheel. I looked at the store and I see WHL-1048 as an option, but the question I have is the sprocket wheel and if it can be taken off the old one and put on this one and how.