The broken blue gear can be caused by too aggressive settings.
The parameters to pay attention to are:
Motor acceleration (in all modes).
Startup boost (in power mode).
Torque assist levels (in hybrid mode).
In my tests I tried to exaggerate with these parameters, there were no problems with the blue gear, but I had to be very light on the pedals.
With 860C and conservative settings, since April I have done 1500km (500 with v20.1C and 1000 with v20.1C.3) without any problems.
The problem reported by Hangman for the version with stock display is different.
The motor that gets stuck in acceleration without control and without pushing on the pedals, is a rare but known problem.
It happened in all previous versions, mine and marcoq's.
But only in stock display versions, I have never had any reports of this problem with the LCD3 and 860C, yet the motor control code is the same.
I thought I had remedied with v20.1C.1, unfortunately this is not the case, there is also a report on GitHub to confirm that the problem has remained.
I still haven't figured out what the cause may be, but in the new version I've been trying for 2 months, I've added a function that stops the motor when there is no more control. It will then be necessary to turn the display off and on again.
It does not eliminate the problem, but it can avoid danger and damage.
Before I release it, I want to try a couple more weeks.