HP 34C - strange bug

[Michael Fehlhammer]

My HP 34C shows a strange behaviour: The low-battery-dot that appears at the very left of the LED is always on, also when fully charged batteries are inserted.
This is somewhat annoying, since I have no chance now to know when the batteries really are becoming weak.
Has anyone got an idea where the fault is located and what could be done to fix it?
By the way? I faintly remember that there was a discussion years ago about a thick book with many photos, a repair bible for the old calculators, soon to be released ... called THE book ... is this book available now, or has the project been canceled?