A major pitch raise (or pitch lowering) starts by pre-measuring the pitch of the piano.  Tap on the "Start" button to begin pre-measuring.  In this mode you will see "Over-pull pre-measuring" in the left yellow box.

The right yellow box shows what note you should play for pre-measurement.  Play each note once.  As you play each note make sure TuneLab detects the pitch and then switches to the next note you should play. 

The purpose of this step is to get an idea of how flat (or sharp) the piano is so that TuneLab can figure an appropriate over-pull amount.

To pause the pre-measurement process and prevent measurements from being triggered, swipe from the Current Note Display to the left, the same as if you were turning off auto note switching. Then you will see the following:

To resume pre-measuring swipe from the Current Note Display to the right.

After making pre-measurements you can review and delete some measurements.  TuneLab can work with an incomplete set of measurements, so don't worry if a few notes don't get measured.  The important thing is to make sure that TuneLab assigns each measurement to the correct note, and that you don't get out of sync with TuneLab as these pre-measurements are being made.  If you interrupt pre-measuring, you can resume at any note by tapping on the "Resume" button on the over-pull settings page.  And you can delete incorrect measurements using the Edit pre-measurements button. But often it is best to simply start over from the beginning by tapping on "Start".

You can view these pre-measurements from the main tuning screen too by tapping in the over-pull offset box while over-pull mode is enabled.

Tell TuneLab where the wound strings and the bass bridge end by tapping on the blue round button to the right of the display of the break points. Note that these two breaks are sometimes at the same place, but they are often different.  You can adjust the safety limits for wound strings and for plain strings by tapping on the round button next to those limits. You can optionally specify the location of the treble struts. If they are specified they will be used in the over-pull calculations to reduce the over-pull amount just before the struts, which can improve over-pull accuracy.

If you don't want to pre-measure all 88 notes, you can configure the pre-measurement to choose only white notes, or only notes C, E, G, C, E, G, etc.  Tap on the round button next to the description of what notes are to be measured.

After the pre-measurements have been made, you begin over-pull tuning.  In this mode, there is a display of the over-pull offset next to the current note display.  To exit from over-pull tuning mode, visit the over-pull setup page again and tap on the button that says "Stop using over-pull", or simply tap on the stop button on the main tuning page.

The Over-pull factor is a multiplier that is applied to the calculation of the over-pull offset. A factor of 1.00 means no change. You can change the over-pull factor to a number larger or smaller than 1.00 to modify this calculation as you see fit.