Yikes, I'd be very interested to know how that happened as well.
Ok so it took me about 3 hours, but I was taking the time to to brush and clean the the SF at the same time, I was in no particular rush. I read through all of the documentation supplied with the new componants and also watched these two videos by Harry Soo - The first one gives a good idea of what is involved and the second is extremely important as he corrects a mistake he made.
The new auger mechanism comes with a new base plate that attaches to the motor with four bolts and has two more holes to attach it to the back of the auger chute, these two holes are raised in one direction and it is important to get them the right way around. The two screws that hold the motor to the chute are now supplied with crush washers and these must be installed so the motor doesn't work loose.
Interestingly, this is how to original cotter pin was installed by weber. The instruction for the new one tell you to splay the legs of the cotter pin in opposite directions.
Any questions, let me know!