Hello @dan64,
The px4-esc-cal-tool does not apply to ModalAI uart-based ESCs. That tool was used for calibrating ESC response to PWM control signal for old-style ESCs.
There is no need to re-calibrate the ModalAI ESC if you use a stock configuration, such as the motor + propeller that comes with Starling 2 MAX.
The ESC parameters for this motor + propeller are located here : https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-esc/-/blob/master/voxl-esc-params/D0012_Starling_MAX/esc_params_m0129_f2203_5_1500kv_7x3.7x3.xml
You could use voxl-esc tools to verify this. Since you already ran the spin test using voxl-esc tools, this should be somewhat familiar.
./voxl-esc-verify-params.py
This should query all the params on your ESC and they should match the same param file (which is also stored in /usr/share/modalai/voxl-esc-params/ folder.
From the test spin results, it does appear that a motor may be faulty. I am assuming this behavior happens every time you run the test. However, you can never know for sure that the motor is at fault - it could be an ESC issue. In such case, the best thing to do is to do a similar test with another motor attached to the ESC channel in question. The ESC with the correct params is tuned for this motor + propeller and has been thoroughly tested, so I do not recommend trying to fix this by modifying ESC parameters (this will most likely result in a wasted effort).
You can purchase the Starling 2 Max replacement motor here : https://www.modalai.com/products/starling-2-max-replacement-parts?variant=49704826896688 . It looks like the image for the motor has the wrong kV (2850), but the actual motor kV will be 1500.
The motor used on Starling 2 Max very similar to Tmotor 2203.5 1500kv, you could also replace it with this one without changing any parameters.
Testing a replacement motor should be relatively easy if you cut the motor leads on the motor arm and not disassemble the drone to get access to the ESC. Remove the old motor and solder and heat shrink the connections for the new motor and repeat the spin test (in order to make sure that the spin direction of the new motor matches the old motor, you can mark the wires before cutting and solder the new motor in the same wire order). If you wanted to not cut the motor wires along the arm, then you would need to do some disassembly to gain access to the ESC solder pads. (instructions outlined here : https://forum.modalai.com/topic/4023/motor-replacement-instructions-starling-2-max).
I am curious what the motor spinning actually looks / sounds like, so if you are able to record a short video of the motor spinning, starting from the spin-up (just the faulty ID), that could be helpful:
./voxl-esc-spin.py --id 1 --power 15
Alex
