Replacing the PROPELLER on my Surface Drive Mud Motor (Backwater Performance Systems) 

Self locking nut, the more times you take them off it will wear out the locking feature, its always good to replace when the resistance of the nut starts lessoning. Kinda sounds like you may be having a bearing go out on the drive shaft. With a two blade prop balance is critical as it creates a lot of vibration thru the whole motor. Thats why its not a great idea the grind them down unless you balance them after, would be interesting to see the old prop on with it running at rpm;s, if the skeg looks blurry its shows the blade is out of balance

Whats the purpose of applying the marine grease?

It’s self locking and use the uni wrench correctly

What surface drive make/model did you install this on?

Did you gain any speed with the new prop?

Just got mine. Same prop same motor but the props look slightly different on the side that mounts to the shaft. Did yours also look slightly different?