This prop service kit that includes a thrust washer, tab washer, and prop nut.
 
A Nylock prop nut should stay put. If it doesn't, it's worn out and you need a new part. A loose prop nut can cause the prop to vibrate more. The banging of the prop back and forth can chip gears inside the lower unit. In some instances, the nut can back off and result in lost props. 
 
You should tighten the prop nut to around 55 ft-lbs of torque until a flat nut surface is aligned with a washer tag. You can then bend one tab up on either side.
 
You should not reuse an old worn-out prop nut. Once a nylon lock nut is installed, the nylon insert is deformed; if you were to remove the nut and reinstall it, its locking strength would be lost.
 
Check your thrust washer. The three most common causes of thrust washer failure are contaminants, worn-out misalignment, and overload wear. A good washer is required to prevent movement along the axis of a shaft and transfer the thrust from the prop directly to the shaft.
 
Part Numbers:
11-52707A 1, 11-52707Q 1, 11-827614, 11-827614A 4
 
Includes one (1) Brass Nylock Prop Nut, one (1) Tabbed Washer, and one (1) Brass Thrust Washer.
 
Contact Mike Hill at STVracer@yahoo.com with any questions