Are you sure there is no solder bridge anywhere?
Maybe you switched the transistors?

If all the other digits are working fine without Q7, the display glass should be fine.
Replacing both transistors would do the trick (most of the time)....

If you move the display to another players position, does the problem go with the display or stays at the same players position?

As the defective transistor activates the ones digit all the time, all the info from the MC14543 decoder goes to the ones digit.
That explains why it is lit so brightly all the time.
When in attract mode various numbers should be displayed at the other positions, but the defective digit draws all the info.
That's why it seems to be altenating between 0 and 8.
In test mode it gets the correct same information for all digits, so you do not have "overlaping" information.
Thus it seems the MC14543 is working correctly in giving the correct information.

You can test the transistors with your digital multimeter in diode setting.
Easy to compare with the other transistors.

Good find!

Just to be clear for future reference....
R1, R3, R5, R7, R9, R11 should be 100K ohm, not 102.2 ohm.