Any Ideas on how to prevent VEX gears from stripping?

For VEX Turning Point we built a flywheel robot and it puts a lot of strain on the driver gear and the square insert is stripping. Any ideas on how to prevent this or make it happen less often would be great.
(This has only happened twice after continuous use over the course of the whole VEX season so its not detrimental but I’d prefer to avoid problems and not waste gears thanks)

Lock Bars

Link to product on Vex Robotics page

Thank you its a big help

The new gears (hs) have metal inserts, which should also help.

High Strength Gears on 1/4" shafts need HS Lockbars from