I did try trim & also subtrim with no positive effect.

When turning on the tank, once it connected to the transmitter, it'll fire boom cannon, repeatedly with interval between shots. So the throttle stick, the multifuntion stick, not in correct position from the get go. The throttle stick is centered correctly which I confirmed with my other rc vehicle. Also to note that when I moved the throttle stick up & down, pretty much like throttle stick calibration, I'm able to trigger both engine on/off & machine gun. However, whenever I triggered the boom cannon, I'll need to do this all over again.

I think I want to try extend the throttle stick travel >100% again. I did tried it before without positive effect though but I probably didn't try both up & down at the same time.

Edit: so far I found that-

• cables that connects the receiver & tk22 are fine.
• Consistency where whenever I fire the cannon, I will need to do throttle stick calibration afterward.
• This is more of theory because I don't have another dual-stick transmitter to test but I think this issue more like radio issue or specifically compatibility issue with the radio I have which is Walkera Devo 7 & tk22. Unlike standard ESC, tk22 forgets the throttle stick calibration whenever I shoot cannon.

Btw, which transmitter you guys use with your tk22?