Fixing a flickering led
Based on what I read here, I have just successfully brought my Revo Blik back to life by replacing the backlight LEDs with 2x Bright White 3mm LEDs (£0.84 each from Maplins).
A window scraper blade happily cuts the adhesive that holds the LCD/Backlight/PCB together. The LCD folds out by 90deg. The backlight removal was the biggest problem as the two existing LEDs proved very difficult to unsolder. For insertion of the new LEDs I drilled the holes out to 1mm. and used high lead solder (old stock).

With the old diodes removed, the +ve voltage was +5.1V . After the new LEDs were soldered in, the anodes were at +2.24V.

The screen is now fully readable. Thanks to all previous posters for the guidance that led to my success.
Bob