When you say all was working fine, I assume you mean both motors turned and the tail blade spun normally, so the motors arent fighting each other and the gear isn't too tight.
Now you say you are getting voltage to the motors--are you measuring this at the motors or at the connector at the 3-in-1?
If you are measuring at the unit I'd say check the wire in the tail boom. If at the motors, I'd say the motors are fried. They aren't very good motors to begin with.
Try testing the motors out of the circuit to see if they spin.

And when you want to really improve your performance try the DD system.
I put some test results over there:
http://www.rcuniverse.com/forum/fb.asp?m=5079804