I have several end users with HP Scanjet 7000s2 in LF client 9.1.  When one of these end users scans pages, they come out significantly darker than everyone else's scanned pages, even the exact same pages come out noticeably darker when scanned on problem scanner. The pattern of darkness is pretty consistent over the whole scanned area of the page, although it is slightly patchy (i.e. some parts of the page have more or less darkness, but the whole page is often too dark to begin with)

First I tried putting one of those alcohol soaked sheets the HP gives you through the scanner. No difference. also tried carefully cleaning the inside by hand with the HP alcohol sheet. No difference.

Then I tried checking the bringhtness/contrast settings on the problem scanner, both of which are set at -1000 under File > Scan Settings (see attached pic). First, these settings are identical to the other end users, so probably not the issue. But I decided to try raising the brightness to see if it made any difference. However, when I change the setting and then open the File > Scan Settings window again, the brightness is right back to -1000.

Is there another way to change this setting so that it actually changes? Am I missing something else? Any ideas would be appreciated. Thanks!