As ForceFlow hinted, you're missing bit 0 of the display BCD data from the MPU board to the displays. This signal is wired from pin 25 of connector J1 on the MPU board and goes to pin 19 at each display. It's used to select even/odd numbers at the displays (it appears the displays are seeing this signal stuck low causing odd numbers not to be displayed).

If you wiggle the MPU J1 connector, do the odd numbers appear?

This signal is "PA4" which comes from pin 6 of the U10 PIA chip on the MPU board.
This signal is also used to select feature lamps and is one of the switch strobes.
Are all feature lamps and switches working properly?

If you have a logic probe, check pin 19 at one of the displays connector. It should read high pulsing low and should be the same reading back at pin 6 of U10.
If you don't have a logic probe, try measuring the voltage with a multimeter at both of these points - they should read about the same. If they don't you need to trace where your open/short is.