You should check your batteries in the transmitters and the plane. Your ESC could be bad. Make sure your receivers are not getting hot. The 624 is not suppose to be wrapped in protective foam. During normal conditions they need to dissipate heat.

Have you range tested your transmitters? If not do so.

Rebind the receivers. After you rebind the receivers make sure that the fail safe function is set correctly. If it is not follow the binding instructions on changing the fail safe function.

Run the engine on the ground at 3/4 to full throttle and see if you experience the same issue. If you do then start replacing components one at a time until you find the problem.

I would bet that if you starting using your 400 transmitter you would see the same problems. This would mean the issue is not transmitter related.

It is highly unlikely that you have both a 600 and 650 transmitter that are both faulty. And to have multiple bad 624 receivers is also highly unlikely.

My Tactic 650 and 624 receivers are rock solid.

Hope this helps.

todd