Missing LCD rows and columns; repair?

[mfleming]

This condition is often the result of the failure of the conductive "zebra" strip connecting the LCD connection pads to the main PCB pads. Try pressing around the (upper, lower) outer edges of the display bezel to see if the columns of pixels reappear at a certain point. If so, you have a connection problem. This can be fixed, but will involve some pretty heavy effort to open the calculator case, as it was not meant to be opened and repaired. There are a number of articles describing the repair process, but first see if the diagnosis is correct.