Hello. I have a Sig Extra 300XS 1/4 scale plane with a OEM pull-pull rudder system. I have tried making the wires moderately tight to very tight. No matter what, the rudder will not come back to absolute center. Say I give full right rudder, when I let go, the rudder won't return back to neutral. Same with the left side. I have tried trimming and sub trim. Nothing is working. I feel I need more tension but I have it I believe way too tight right now and the problem is still there. Does anyone have any suggestions?