UM Polecat wont stay bound to TX

[Davethebluessinger]

Hi guys,
I bought myself a used PZ UM Polecat off ebay, it was a little beaten up on the stab but with some Cyano and a little bit of carbon I've got it looking pretty good. The reason i didn't buy new? well I want to try a little lunchtime flying in the park over astroturf and I figure once I'm happy with the size of the area I'll be using and when I've had a little more practice with the Polecat then come springtime I'll buy another Bnf. I have a minor problem though. This little plane wil be residing under my desk permanently. I don't want to leave my "proper" TX there as I have a few other planes at home that I need to use it with. So I have an eflite controller that came with another DSM2 UM model lying around - ideal for taking into work and leaving in my draw.
I bound the TX to the Polecat and everything works fine, but when I change the flight battery the plane loses bind with the TX and I have to rebind. Not a major problem to rebind between flights but a bit tedious.
Any ideas on why the plane keeps losing bind?

Cheers
Dave

[Wildflyer]

It definitely should not lose bind, I would call Horizon Hobby support, even though you bought it on eBay, they either won't ask or don't really care. They have modified a 8103 transmitter and replaced a 2.4 tx module without question, and returned them for free.