I was installing props and found out one of my motors didn't feel right. It felt stiffer and didn't move 'robotically'. When the motors started, it squeaked on and off at idle and disappeared when revved up. As a cautious person, I bailed and called it quits for the day. I took her home and had a closer inspection. What was happening was small black metallic filaments was shorting out the magnets and causing changes in polarity. If there is a heavy bias on polarity, your motor will lock up in mid flight. At first I, tried to remove by tweezers but it was impossible as the magnets are too strong. I tried disassembling the motor by removing the C-clip and ring but the bell housing wouldn't budge. I am sure there is a method but it would involve prying to separate the bell from the coil. I ended up using an air compressor to move the filaments to the bottom of the magnetized motor. I then used tweezers to slide them out and then sticky strong tape to lift them off the bottom of the magnet. What I cant figure out is how I got the motor contaminated in the first place. Also, does anyone know how to disassemble a P3 motor? All youtube clips are for other motors and it seems easy as removing the c-clip, washer and then separate by pulling.