Generally speaking, you would pull the auger and impeller shafts through the front -requiring that the driven pulley be removed. Considering the fun you seem to be having with the bolts, the pulley is likely rusted on the shaft. I would soak it with your fave penetrating oil seeing as though you have the time. The pulley is keyed as well as being retained w/ the set screws. There will be a flanged bearing supporting the shaft. Many of the chassis you split 1st- depends on the model.

Go to the Sears parts site and plug in your Sears number.
It may have some exploded views.

Thanks for the advice. After breaking the machine into halves (the motor/wheels/handle and the impeller/auger/housing), it became much more apparent that the driven pulley will be the best thing to pull.

As you said, it's there with 2 set screws and a key, and lots of rust. I can't build enough torque to get the screws off with my cheap-o allen key set, so I'm going to invest in some sockets (or at least one). Unfortunatley, every Sears within 50 miles of me is out of stock on the Craftsman 5/32" hex bit socket. I'll probably just wait it out and play with the rest of the thing in the meantime, which may provoke more questions, so I may be back.

Thanks again for your help.

In order to pull the shroud from around the carb, I need to remove the choke dial knob. I'm having trouble removing it, and I'm afraid to force it. It is difficult to tell whether it is press fit or screwed onto the lever. Any suggestions as to how these are generally fastened?

For this and future reference, the blower is model 536.884780, with a 143.965003 engine.

536 is AMF/Murray
The engine is a Tecumseh HSSK50-67338P

Just to add-
You can get an engine service manual here-
http://www.cpdonline.com/692509.pdf