The SL611 calibration adjustment instructions which I have are what I use on the SL612 test jig, but they can also be done in the console. -And no, they were never included as part of the standard manual so far as I know, but they were written as a specification/standard for in-house testing/calibration, and were shared/leaked fairly generously over the years.
For center-section calibrating of the PSUs, either walkie-talkie or cellphone/intercom an assistant...
...OR...
Run a 6-conductor cable from a panel in the machine room to the console center section, and tap it to "sniff" the rails. -For a one-off calibration it gan be temporarily tacked-in at the console end, and run through doorways; -in a better-planned installation, this can be made permanent, and available on the wall to maybe a pair of probe sockets and a 5-way switch, with +18, -18, +13 +48 and +250(x10) on it... with a 9-meg resistance in series with the +250 line. -Plugging a 1mΩ input impedance fluke meter in to this socket for example -just like a scope- will cause +263 volts to read 26.3V.
This can be used to measure AND read from the machine room... on a panel next to the power supply changeover unit for example.
When setting these up, I like to power off approximately HALF of the buckets for a 2-PSU setup. That way each respective PSU inder test is supplying approx. 50% of the total load, which will reflect its anticipated load once both supplies are on. For a 3-PSU setup, popwer off two-thirds of the console, and so forth.
If you REALLY want to make things super-fly, you can build in a digital panel meter properly accommodated, next to the rotary switch. -I have an LCD unit here which I've been MEANING to get round to doing that with...
...-one of these days... (sigh!)
Keith