1997+ Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-826148R2, Page 305Get this manual
8Install locknut and washerTorque nut to 40 lbft(54.2 m) Trim Tab Adjustment and Replacement
IMPORTANT: The trim tab is made of special alloy to aid in protecting the drive shaft housing and gear housing from galvanic corrosion (corrosion and pitting of metal surfaces)Do not paint or place protective coating on the trim tab, or trim tab corrosion protection function will be lostR eplace trim tab if 50 (or more) consumedMark location of old trim tab on anti-ventilation plate before removal; install new trim tab in same location1C heck trim tab position as follows: aO perate boat at the spe ed at which it would normally be operatedbIf the boat pulls to the right (starboard), the trailing edge of trim tab must be moved to the rightIf the boat pulls to the left (port), the trailing edge of trim tab must be moved to the left2If necessary, adjust trim tab as follows: aShift engine control into AL and turn ignition key to "Oposition