I just posted in the other post about the st824 and the augers not turning. In there, I posted links to what I believe is the service, parts and owner manuals for this machine. It should tell you how to replace friction disc. AS for remove the pan, tip the unit in service position ( standing up on its bucket) and then should be bolts holding the pan on the bottom. Remove them, look in at the guts. :) Before putting in service position, I like to shut off fuel valve and run machine dry. I make sure the fuel and oil cap and tight.
Without having the exact model and serial, I believe the below may be your
parts manual.
http://apache.ariens.com/manuals/PM-24-89.pdf
This is your
service manual.http://apache.ariens.com/manuals/000123A.pdf
And
owners manualhttp://apache.ariens.com/manuals/024532.pdf
Cheers
Goofie Newfie