Take out the router. Loosen the screws holding the nut. Twist nut slightly - hold, and snug screws back down. Apply some dry lube to screw. Run Z up and down a few times. Replace router and test carve. Results same or better?
Take out the router. Loosen the screws holding the nut. Twist nut slightly - hold, and snug screws back down. Apply some dry lube to screw. Run Z up and down a few times. Replace router and test carve. Results same or better?