so this has been bugging me for a while and im kind of at a loss. built a 4inch cinewoop a few months ago, been flying it fine, and recently one of the motors just starts cutting out randomly. sometimes its on a hard punch, sometimes its just cruising around and it stutters. i resoldered the motor wires to the ESC pad twice now and visually the joints look decent, shiny, good coverage. the motor itself spins fine on the bench when i run it through betaflight motor test. i swapped the motor to a different ESC output and the problem followed the motor so it seems like the motor but then why does it spin fine on the bench... the stator feels okay, no grinding, magnets seem fine. flying on 4s if that matters

could be a partial wind short or a hairline crack in one of the windings that only shows up under load. bench testing at low throttle wont necessarily catch that. the heat and current draw during actual flight is way higher than what motor test in betaflight puts through it. id try running the motor on a proper load, stick a prop on it and throttle it up secured to something, see if you can reproduce it on the bench that way. if it still cuts out under prop load then yeah probably a dying motor. 4 inch motors take a beating especially if youve had any crashes

also worth checking if your ESC is logging anything - if youre on blheli32 you can pull the log data and see if theres desync events or overcurrent flags on that specific output. could narrow it down to whether its actually the motor or the ESC output having issues. not all ESCs have great logging but worth a shot before you buy a new motor

also have you checked the motor screws? had a similar issue once and one screw was barely holding on and the stator was slightly loose. drove me insane for two weeks