1987 Johnson/Evinrude CU Outboards 35A thru 55 Service Manual, Page 272Get this manual
General Safety Warnings
Replace any locking-type fastener (such as locknut or patch screw) whose locking feature becomes weakDefinite resistance to tightening must be felt or locking fastener is not suitable for continued useReplace only with authorized replacement part or equivalent See Safety Section Part A" for ways your work could lead to injury of the boat operator, passengers, or bystandersII