I have a Minn Kota edge on my small boat, the motor is sliding back and fourth inside the armature about 1/2 inch causing the prop and prop shaft to stick out about the same distance and producing a large gap between the prop and armature, also grinds the prop when popped out, i can slap the prop and knock it back into place, but it eventually pops back out again about the time i hit my next stump. I took the motor apart every thing i could see was tight. I cant figure out what holds the motor secure inside the armature and why its sliding back and fourth. Any body know how to fix this?