Steering servo not centering

[Cardnim]

Hi folks,

I have just installed a Savox 1258G into my Schumacher Cat.
The tx is a Etronix Pulse 3ch 2.4Ghz (also new to me)

When I centre the servo and then steer, the steering returns to a random location. By that I mean that it seems to never return to centre, instead stopping a little from it.

Adjusting the trim can help until you turn the other way and then it goes off again!

Any thoughts or advice massively welcome.

Thanks.

Andrew