I am not sure if you are having the same problems as I had. I could not get mine to stop spinning and this was what the problem was:
http://trextuning.com/phpBB2/viewtopic.php?t=3575
Have a look at the tail rotor setup and see if you did not do what i did on construction.
If not this forum is also great for lots of help from other T-Rex flyers.
Kevin