I was enjoying my first flight with my new to me 73" QQ Yak and a brand new DX7 with a 7000 receiver, (my first ever flight with 2.4).
About three minutes in, I had no elevator and the plane went straight in and was destroyed. Upon inspection, I found that the elevator channel was not functioning at all and all other controls were functioning properly. I was running two servos for elevator under a p mix, using the elev. port and a aux port on the rx. I confirmed that all connections were solid. I then unplugged both elev servos and plugged them into each of the other control ports (th, ail, rud) where they functioned perfectly. I then plugged each of the other servos (th,ail,rud) into the elev and aux ports and they did not function at all. Then,just like that, the elev channels began working again. I have sent my tx to spektrum and ordered a new plane, and I am wondering if anyone has ever heard of losing control of only a specific control.

Sounds like something just went bad. Sounds like more of a receiver issue than transmitter. Hopefully you sent the receiver in also. I usually will "fly" a plane on the ground with a brand new receiver working the controls for a couple of flights worth of time since many times if a piece of electronic gear is going to go bad it will be in the first hour of its use.