I had this same pinion problem last week at TCS in Vegas. I had a binding in the drivetrain and couldn’t figure it out. Changed spur, gears in diff, took both front and rear apart and rebuilt... turned out that the pinion was worn out! How does a metal pinion wear out against plastic spur??? This caused me to miss both qualifiers and ended up last in C-main lol. Can’t race tomorrow at Revelation Good luck to all and have fun.