Epson Z8250NL - Manual (Page 126)

Image Maintenance
126
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After adjusting all four corners, select [Exit], and press the
[Enter] button.
If your projector requires additional adjustments, choose "Select
intersection and adjust" to perform a detailed correction at any of
the grid intersection points. Use the arrow buttons to highlight any
of the intersection points and press the [Enter] button to select and
begin adjusting that point.