Hello alastair, welcome to this forum. Like many of us, you must have been 'lurking before posting' since you joined last year !
Lots of Quad folks, and CB owners in particular here to help. Noises during the auger turning always seem to make the motor suspect. CB 1200's in particular seem to have a history of auger motor failures, for whatever reason.
It's still worth ruling out an auger obstruction as a possible cause of your squeal before you start 'throwing parts at a problem" (been there, done that ........). Sometimes, 'if Murphy takes the day off',
a simple fix is all it takes, so start with the simple stuff ! Another member posted a thread a couple days ago that had a spoon end up in the hopper, and then into the auger - it's amazing what can get in the hopper by mistake.
If you have a small mirror, hold it at the bottom of the pellet drop chute inside your firebox and shine a flash light beam off the mirror to look up the chute and see if there is something blocking it at the top. You can pull all the pellets out of the hopper and look up the bottom of the auger screw and see if something is obstructing / binding it up.
If you don't see anything obviously obstructing the auger on either end, on most Quads it's generally not a major deal to take the auger assembly out to check for any possible obstruction in the middle of the tube, as well as 'bench test' the motor function to see if it reproduces the sound you're hearing.
The auger assembly is held in by two bolts on fixed screws that mount the auger bracket to the stove body - I found a couple pics of it below, as well as a diagram of the auger parts, that are on pg 43 of your manual. (broken link removed to http://hearthnhome.com/downloads/installManuals/7014_179.pdf)
With the auger out you can check the allen head set screws that hold the auger screw to the auger shaft and the collar shaft to make sure they're not loose, or stripped. Assuming you've got some electrical knowledge, and are comfortable not 'defibrillating' yourself
you can *carefully* hot-wire your motor once it's out of the stove to 110 V power, using a cannibalized extension cord jumper. If your auger reproduces the squeal out of the stove you've confirmed it's the motor going bad.
With any electrical troubleshooting, remember to UNPLUG the stove before disconnecting any wiring, to protect you and your $$$$ control box !
Good luck, and keep us posted.