Airtronics TX/RX problem.
 

I have an Airtronics MX3 FHSS 2.4ghz TX.

The issue I have been having is that some of my recievers (when I turn the power on the buggy/truck) seem to take a long time to sync, to the point that this has caused ESCs to go runaway and has made it very difficult to calibrate ESCs.

Now the simple solution would be the RX is bad. However I have sent two of the RXs back to airtronics for repair and been told they are working fine.

Now I would think then that the TX is bad, save that I have approx 8 other of the same RX and they work fine. I have rebound the ones that are giving me issues and they will be fine for the first power on or so then go back to having trouble syncing.

Anyone have any ideas?