Well, I won’t say it was easy, but I believe I’ve managed to get the roadbed pretty flat through the north end of Pembroke. As I mentioned, the roadbed was glued and screwed (from above) onto the benchwork, and the screws particularly made the work tough. I also found that the contortions I had to undergo to work above my workbench were severe (though not as bad as if I’d had to work inside the book shelves).
I had to modify four transverse members of the benchwork. The two northern-most ones turned out to be relatively easy. They were screwed to the lower section of the river from below. So, I cut them with a saber saw just beyond the tracks, and pried them off the river.
The southern members were another matter. I couldn’t simply cut them vertically or the layout would have fallen apart, and the roadbed was screwed in from above. I tried cutting the screws with a hacksaw once I found them with my cross-cut saw. That didn’t work, and I wound up exposing their sides by cutting the benchwork with a knife; I then ground them off with the Dremel. Two of the enemy casualties are shown below.
Finally, I had the roadbed free to move up and down, and I needed to shim it up. I measured and cut some sections of spruce. The northernmost two are simply screwed in from below. The southern pair needed new cleats created.
Now, I need to go back and check the track gauge throughout. It is unlikely to have stayed correct through all this bending.
Before:
After:
Pembroke:87 
Oh my! At least it is done now and you can gather forward momentum. Cheers,
A Hutchinson
Yes, a cursory review shows that I have some minor gauge corrections to make, but nothing too outrageous.