I tried increasing SC scaling by 30% from standard pp200 (1.0e-8 => 1.3e-8) while holding the GL steady. The result is some remaining undercorrection: DCAs of about -300 microns at bbcsum=1.5e5, and ~0 at bbcsum=4.0e5. Conclusion is that this is pretty good, but we can do a little better. It appears to me that the offset needs to be decreased (actually, a linear fit to the uncorrected plots suggested this too), and the scaling also by just a little bit.

The attached plot shows the DCAs vs. bbce+bbcw for no correction (red), standard pp200 correction (blue), and the 30% trial correction (magenta).