Regarding the tail drive gear (shaft, bearings, and pully), I had the same problem. It didn't seem to damage the belt at all, but because the nylon pully was slowed on a very rapidly spinning shaft, it immediately wore the center of it so it now slips on the knurled shaft. I have removed it already and found a shortcut to splitting the whole frame.

Remove the four screws surrounding the tail boom mount. Use a sharp blade to cut/pry the gyro from it's mount, making sure to note it's orientation. Remove the four screws from the tail drive gear bearing area. Loosen the four screws from the areas of the main shaft bearings. Remove the rear left screw from the landing skid mount. Detach the ball link from the left side of the swash plate, the one from the left side servo. Remove the two screws from the left side of the anti-rotation bracket. This should allow you to gently pull the back of the frame apart enough to remove the tail drive gear assembly by reaching in and slipping it down out of the belt loop and back out of the frame. When replacing it, be sure to check the tail rotor rotation direction by spinning the main blades. My belt likes to flip over the other way for some reason once it's free, and if I don't catch it, I have to take everything apart again to twist it the other way. Use foam tape to place the gyro back where it was.

Hope this helps.