T6EXHP Channel 1 DTRM Setting trouble

[Lord Arioch]

Hi,
I am seeking some help and advice on my Futaba T6EXHP Channel
DTRM Settings.
When I set the DTRM zero every now and again the DTRM will retune
itself to +120 this only seems to happen on channel one.
Can some one tell me if this is a Fault or a wrong setting on the TX
that is the cause?

thanks

Lord Arioch