I have the similar experience. The Caliber 30 was not able to take off after my third flight on the field last friday. I found out the tail rotor was somehow twisted 90 degrees. The servo was not able to move it at all. One of the set screw was also gone. I had to twist back the tail rotor 90 degrees back. I still have not figure out how the tail rotoer assembly was able to be twisted at the angle. I put another set screw in. Test flight, no problem. I think it might be the design error.

Good observation,

Chris