: my strongback is not perfectly flat. I
: have a framing square that I can use to check vertical-ness of
: forms by measuring with the top string (can't use bottom string
: or strongback because the other stations are in the way).
: Several of the forms are slightly off vertical.

With my system it doesn't matter if your strongback is straight or twisted.

Stand OVER each station and sight down the vertical line on the station and
align the station line with the top and bottom string lines.

This assumes you have properly plumbed the upper line with the lower line first.

Rob