After I glued the transparency foil pieces to the back of the displays, I fixed them with carpenter clamps:
And after extracting them from the clamps:
Then I replaced R14 and R16 with 3.3kOhm and 1.5kOhm resistors to adjust the display voltage to reduce the intensity of the LEDs. See this blog entry for details about the adjustment procedure:
Then it was time to solder the displays back in. The insertion of the displays back into the board is tricky since one needs to line up all the pins at once...patience and calm music pays here...;-). Here is the display board after installation:
I adjusted trimmer R15 to get about 3.1V keyboard strobe (yellow) and about 4V on the LED rail (blue). It is important that the keyboard strobe does not go below 2.7V (see above blog entry for a discussion):
Looks like we are almost done. The last step before I put it back together is to check on the processor board.