It is becoming more common to see excessive thrust wear in transmissions with people using old oil, or running low on oil. Thrust wear will cause the gear to walk and pop out of the slider. Many people with old transmissions complain about the shifter popping out in 1st or 2nd gear. It is most likely the thrust worn on the hub, picture below. The hub on the right is worn, and the one on the left is good. You can see where the gear thrust surface just dug into the hub. In most cases, we can clean up the gear and just replace the hub with a new one. New 1st and 2nd gear hubs are included in all of our rebuilds!!
