I was taking my DIY board on its first test run. It is a 5055 10s sensored motor running FOC on the VESC.
I was going up a steep hill (I believe about 10-15% gradient) and heard a strange clicking followed by a strange whirring sound coming from the motor. After dismounting immediately I found that the motor seemed to have pulled itself apart and the shaft was out of place (see attached).
Like @scepterr said it looks like the grub screw has stripped on the shaft and it has slid outwards. If you can’t get the shaft out you could try using grub screws again or use red loctite and never worry again
I think the set screw on the rotor(nipple) wasn’t tight enough on the axle and so was the glue that held it together. Maybe try and push it back and reapply loctite like @pat.speed said. Next time use a 63mm for hill climbing.