ive been chasing this issue for honestly like three weeks and its driving me mental. one corner of my quad randomly twitches, not on every flight, sometimes its fine for a whole battery then it does it again. happens at different throttle levels, doesnt seem related to temperature or anything i can figure out. already re-soldered the motor leads because i thought it was a cold joint and that didnt fix it.

the twitching corner is always the same motor/ESC combo. i swapped the motor to a different position and the problem moved with it which made me think motor, but then i swapped motors back and put a known-good motor on that ESC and the problem STILL showed up on that corner. so now im confused because that points to the ESC but why would it have moved when i swapped the motor.

running a 4in1 so i cant just swap the ESC out easily. betaflight doesnt show anything obvious in the logs that i can see, motor output looks normal. im losing my mind a little bit here

the fact that it followed the motor initially and then showed up with a different motor on the same ESC corner honestly does point to the ESC pad or the ESC phase itself. 4in1s are a pain for exactly this reason. have you checked for any lifted pads or hairline cracks around that motor output section? sometimes after a hard landing the PCB flexes enough to crack a trace internally and its totally invisible, the connection is intermittent rather than dead which explains the random behaviour

if you have an oscilloscope or even a current meter you can watch what the ESC is actually outputting on that channel under load, that'll tell you pretty quick if its sending garbage signal. otherwise you're kind of guessing. might just be time to replace the 4in1 if its been through some crashes, sometimes its the economical answer even if its annoying

wait when you say the problem moved with the motor the first time ? did you swap to an adjacent position or diagonal? asking because sometimes what looks like a motor issue is actually a FC issue with how it maps the outputs and moving diagonal vs adjacent changes which ESC channel is involved. probably not your issue but worth knowing exactly what you did

also what FC are you on, some of the cheaper stacks have known issues with motor output noise on specific firmware versions