[RC-Monster Mike]

The press pins in the input shaft gears have been known to fail on occasion(usually after upgrading the rest of the drivetrain). There are a few ways to fix it, as mentioned in this post already. I usually replace the pin with a heavier pin and forget about it. I have never broken the pin twice(upgraded pins last and last). The stock Traxxas pins are pretty thin, actually. They weaken and break after a bit of high power running.