Not exactly. But, a chap at the model boat club in Bury UK who has the same ‘Microzone’ controller, said that the top left switch on the controller will set the rudder to 50% or 100%. When I set it to 50% I no longer had any issues. So, I’ve not messed with it since and it’s been fine.
Thanks to all for help.

Hi, I would check to see all the linkages are free and move easily. If thats OK then it must be electrical/sending signal etc. I have very little knowledge on this but maybe just start by replacing some of the components. Good luck. Cheers Ian

I, also did the same thing. I use the bends to tune the pushrods.

Hi guys, I'm really enjoying the information you've provided in your posts, thank you so much.

I do that two on my models. It just wasn’t clear what he meant by the comment? I was thinking he somehow “double-routed” the servo to the receiver.

"double routed" :
I would guess to mean that push and pull cables or pushrods were installed between the servo and the rudder arm. I have done the same on my Juneau model. It appears balance the load on the servo arm and hence the output shaft and gear wheel of the servo.

What do you mean by “ double routed”?

Bonjour Peter,
Now I'm sure the Swiss will add his two cents . . 🤣🤣🤣
But I had the same problem and took my servo apart at the time.
I was amazed at what I saw: the plastic gearwheel with stop cams had cams and teeth missing. .
However, since I double-routed this from the servo to the rudder, I have never had any more problems. .
I also replaced the old servo with a stronger one.
Greetings hobbyists
Michel-C.

Ps: Simbol picture

First, what brand and model radio are you using? If you disconnect the rudder servo arm from the servo, can you cause the rudder to move in either direction further than the servo would move it? Does the rudder move freely?
Quite a few people tend to set up their models with the rudder servo trying to move the rudder to extreme limits. This should not be done. It is very hard on the servo, sort of like trying to force a closed door beyond the jam, AND it causes the servo to draw a lot more current than1) it should, 2) the on board radio battery, or BEC, can supply. Either way, the servo stalls and now the receiver is not receiving it's share of power and, well that is when rc airplanes fall out of the sky.
I hope this helps, but there are numerous components to your radio, model and assembly that can figure into this issue.

I would have a guess and say the rudder servo is stalling and the receiver has a 'brown out' and the reboot of the Tx resets it.. I would check the Rudder endpoints to be sure you are not DRIVING the servo beyond the mechanical limits of the installation.

BTW.. What Receiver and battery are you using??