1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 192Get this manual
it General Safety Warnings Avoid accidental starting of engine while servicing; twist and remove all spark plug leadsWhen using shop air for cleaning or drying parts: Be sure air supply is regulated to not more than 25 psi (172 kPa) Be sure you use appropriate eye protection to avoid personal injuryReplace any locking fastener (locknut or patch screw) if its locking feature becomes weakDefinite resistance to tightening must be felt when reusing locking fastenerIf replacement is indicated, use only authorized replacement or equivalentRefer to Safety Section, Parts and B, for additional safety considerations