Does adjusting the contrast potentiometer (marked 22k at the top of Limbo's wiring schematic) have any effect on the right-hand side of the display?
From the photo, it looks like the right-hand half (8 character columns) are faint (low contrast) but the left-hand half are OK. Can you take another photo? Make sure it's properly focussed so we can easily see the characters - you may have to hold the camera a bit further away from the display.
It could be that the display is slightly damaged. If the display always shows the correct characters (ie not garbage) but half of the display is faint, the display module might be damaged - maybe one of the driver chips is damaged or there is a scratch on the circuit tracks or the LCD glass is not firmly mounted in its frame.
I agree with mattcro, it looks like the lcd is not seated properly. From experience, I doubt the LCD driver is bad. Usually when that goes bad the whole display doesnt work.