Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 330Get this manual
Trim Indicator Gauge Needle Adjustment 1Turn ignition key to "RUN" position2Tilt outboard to full "IN" positionNeedle of trim indicator gauge should be in full "IN" position3If not, tilt outboard to full "OUT" position to gain access to trim sender and engage tilt lock lever4Loosen trim sender screws and reposition trim sender