I also lost my bow-thruster propeller after overhauling the whole thruster with new bearings and lip seal.
When in the water I used it less than 5 seconds and suddenly the revs went up on the motor. There was nothing in the water to get into the propellar so I do not know the cause. When taken out the thurster shaft I found no propellar, but the center piece with still three of the nylon screws on. Strange that means that the whole center of the propellar that should be the most massive part has burst into pieces. Can it be a miss in the production?