Quoted from Femund:But they are different with no pattern each time
Do you have batteries in it to hold the high score/replay levels? Not as familiar with atari's pin games.
If they don't specifically clear regular score memory at bootup and it's not something that's battery backed, it's just going to show random numbers as you note, and any blanks would be digits that can't be displays (hex digits $A-$F)
The rom could be modified to fix this if there's space in it.