I looked at residuals with the default GG voltage and keeping all 45 padrows. Results indicate that alignment is bad (or procedure did not work as expected). One can see significant shift between inner and outer padrows and also significant angle between inner and outer padrows. One can also see that residuals for outermost padrows show some structure. One of the speculation was that some distortion which produces structure at outermost padrows affects the tracking and makes alignment looking bad. Idea was to repeat this study excluding padrows 40-45. Result is shown on the bottom plot.

In all this study hit errors on the inner padrows are increased by a 1000.

All padrows. GG at default voltage. FF.

Padrows 0-39. GG at default voltage. FF.