When I was up there (didn't make Corcoran, BTW) I went directly up from the sandy flat to the base of the Obelisk, then closely followed the cliffs, keeping the Obelisk on my right, into the cirque to the left (west) of the Obelisk. This route avoided much of the extremely unpleasant scree, and lead me to a nice granite dike that crossed the cirque over to the big ridge jutting east from Corcoran.
I had already been up Tuttle Creek a few times before I read Secor's book, so I ignored the book and just followed my nose.
Here's a map I made of the area, and of routes I've followed. The route into the Corcoran cirque is marked in purple near the Obelisk. I descended more directly through the scree (marked in red).
Thanks Tom. My previous experience with Tuttle Creek was to do Langley, and I guess I didn't pay close enough attention to the terrain on the North side. I'll be heading up there again soon, taking your route...
For anyone planning an ascent from the South Fork of Tuttle Creek per Secor's "North Notch from the East" route, I ran onto a serious glitch. Secor shows a map specifically directing that you head up the chute to the right of the Tuttle Obelisk. I did so and climbed up for over 1500 ft to what I expected to be a pass over to the bowls at the base of comb ridge. In fact a came to a huge drop off from where I was looking across the next huge gully system - the one uphill of the Tuttle Obelisk and obviously the one I wanted to be in. Oh well, nice view anyway. I would have been better off reading the topo map instead of the guide book.