I was able to take apart a spare gear box and use the gears inside to repair Bruce's Panther gear box. This is not a difficult as it sounds. The gear box unscrews easily. Just be sure to not to mix up the gear combination, and use the other gear box as a reference. I did have to move a gear on the drive axle, so I used a gear puller ($15 at a local hobby shop) and a vice to install the new gear on the shaft.
That is 3 Panthers now that I have heard of that had their gears strip.
I'll try and post a how to on the tips and techniques.