FUZE Display vertical shift

[Datman]

In my refurbished Sansa Fuze LCD display appears to be a little up shifted in the chassis window, then the first 2 lines are hardly visible when I look in front of it. .wps and .fms have about 2 blank lines, but menu starts from the first line.

I think I only have to add a ui viewport in the .cfg file:
ui viewport: -,2,-,-,-,-,-
but it doesn't work. It does nothing... Why?