Gear is plastic, so I'm not confident a grub screw will have sufficient strength...

You can either drill the bar through to remove whatever pin got stuck and put a new pin. Or drill the end of the bar and tap the hole to put a screw in from the end to trap the gear.

Not clear I'd the bar is removable, so drilling from the end may be more achievable...

Or... slather some epoxy on it and cross your fingers