Ah.... so... are you certain that you're "binding" through the correct PORT of the RX ??? I've known that there could be issues there, and perhaps there is something bizarre going on with the switch.
ORIGINAL: Edwin
Then I would try swapping out things in your setup. See if you can duplicate this on the ground. Then would start with the switch harness. You said it was a heavy duty. I'm assuming it is a three wire switch harness cause you were able to bind. Most of the switch harnesses I have are two wire so I've been modifying them with the third wire. Its basically a swap and try environment. I cant see any way a servo could be the problem, but you never know. I've been following the 2" rule for the antennas to wire spacing. Also, no offense - just cause it needs to be asked, you're not leaving the binding plug installed are you.
Edwin