Hang on there. THis is the HobbyZone version right?
If so go here. http://secure.hobbyzone.com/catalog/...per_cub_parts/
This is the parts listing for it. 4th one down is the prop shaft, 16th one I believe is the whole gearbox assy.
This is very much the same set up as the old ParkZone Cubs used. Just smaller.
As I said before, you boink it, more then likely you bent either the prop or shaft, or drove the prop or shaft back and it's binding up, or you could have even broke the gearbox itself. Any of these would cause the noise/vibration/lack of power you are getting.
Let's start all over. Unbolt the prop and take it off. Now power up the motor, listen and look at the prop shaft. See if its wobbling and if you can hear/feel the vibration.
If not, you more then likely lucked out and just have a bad prop.
If you still hear/feel/see that you still have the problem with the prop off, now it's time to take off the cowl.
Spin up the motor again, and watch the big gear on the prop shaft, if it's wobbling you damaged the prop shaft. Also you may have done more. You'll need to check to see if maybe you damaged the shaft bushings, or gearbox.
Easy enough to do. First look real close at where the shaft runs in the gearbox for cracks or splits. Then look at where the motor mounts for the same.
If you are good there, it's time to check the shaft bushings. Remove the motor screws that hold it to the gearbox, you may need to unbolt the gear box to do so, no big deal.
Once you have the motor off, spin the prop shaft. It should spin very easily. If not, you damaged the bushings, again no real problem. Pop the prop shaft off, and look at the bushings, there will be two, one at the back and one at the front of the gearbox.
If they are damaged, they are easy to replace, but if you hit it hard enough to damage them, you may be better off to replace the shaft and bushings both, or the whole gearbox.
Let me know what you find, I'll keep checking back.