TAZ 6 Extruder V2 - Acceptable Gear Slap

I have about 1400 hours on my TAZ 6 and just noticed that the herringbone gears on the extruder have about 1mm of “slap”. That is, I can move the big gear back and forth by about 1mm on its circumference and hear the teeth tapping against the smaller gear on the stepper motor.

What are the consequences of this slap on print quality? I have a brand new set of herringbone gears. Should I install them?

You should have very little play. Look at the small herringbone gear and make sure it is not too worn as it is the one that wears out first. Then you can adjust the motors position to remove some of the play that is caused by the wear of the plastic. Or just replace the small gear, but look for damage to the large gear. The play affects your retractions and advancements.