On a new FunSR6 from aliexpress, the servo connected to the upper-right arm isn’t holding the arm in position.
When it goes past a certain point, the servo runs continuously but is not applying any power to the arm and the cradle hangs off to the side, still being moved by the other motors.
If I support the cradle to where it should be, the servo stops running continuously but when I let go the cradle hangs down to the side and the servo starts up again.
It looks like there is something slipping in the servo/gearbox(?).
I’ve not taken anything apart yet.
My first idea would be to swap out the servo with another and see if the problem follows the servo, but thought I’d ask here in case it’s just going to be a replcement servo and I should ask the seller for another.
You should contact the seller and they should respond but lets see if I can be of help.
It’s a little difficult to decipher what your trying to portray; do you happen to have a video so I am not guessing?
My assumption from your description is either the PCB pathway or electrical wiring for that particular servo is at fault and may need checking.
It could also be that the servo horn itself is stripped and not latching onto the notched 25T horn thus no movement is transferred.
Here are some questions with troubleshoots:
Does the servo receive any power whatsoever? — When your device is on pay attention the servo spine, does it spin whereas the others do?
If it doesn’t and behaves fully limp, firstly check the wiring for both + & - alongside signal to your units PCB, maybe something is loose.
If the wiring is fine and you have confirmed that than maybe the PCB pathway (pin) is damaged, a way to check this is to swap the signal (yellow wire) over to another pin that is working to factor out issues from + & -. If it works than you know its the PCB and not power supply.
Those two checks should bring more clarity to your situation, of-course a video will help me help you.