I don't have one of these, but I am wondering if she has tried changing the brightness. I found this website with the manual on it:
http://www.ps2netdrivers.net/sewing....piration.plus/
There is a section in the manual labeled Setup with a paragraph that mentions pressing the external Setup button. Select Display, then Brightness & Display, then Contrast. She may be able to adjust the brightness enough this way to make it easier to see what's on the screen.
Does she have the manual for the machine? These instructions should be in there under Setup.