Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 275Get this manual
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 lost
Propeller Installation
Disconnect and isolate spark plug leads when working near the propeller to prevent the outboard from starting 1Apply one of the following Quicksilver products on propeller shaft splinesaSpecial Lubricant 101 (92-13872A 1) b2-4-C Marine 825407A 12) Lu bricant wffeflon (92-
Replace tri tab if 50 (or more) consumedMark location of old trim tab on anti-ventilation plate before removal; install new trim tab in same location1Check trim tab position as follows: aOperate boat at the speed at which it would normally be operatedbIf the boat pu lls 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 left