1. from Dave MacNair concerning bench measurements made on SCOR-6 type corrector power supplies, as presently used in sectors 21-30:

5. Summary
With the standard load, at a 3-ampere setting (half of maximum output), and for frequencies, f, between 240 Hz > f > 0.5 Hz, the SCOR-6 corrector power supplies regulate at an rms of 3×10-5 with respect to their full 6-ampere output scale.
A significant component of this is a 60-Hz ripple.
This regulation improves at a zero-current setting to 0.4×10-5 and becomes worse at the full 6-ampere setting, to 4×10-5.
This is ~10-times better than was originally expected.
It means that these correctors can be used for the LCLS, probably in sectors 22-30, but must be upgraded in sector 21, and possibly sector 22 (work in progress).