1983 Yamaha 30EN Outboards Service Manual, Page 114Get this manual
cMove the shift rod back to neutral, hold the propeller shaft by hand, and give the drive shaft 20 to 30 clockwise turn NOTE: _
1Lock the propeller shaft firmly2Do not turn the drive shaft quickly, or an accurate measurement will be impossible3Take note of the dial gauge readings
This operation is required to give the reverse gear preload
dHold the propeller shaft by hand, push the shift rod downward, and gently turn the drive shaft in and out while pushing it downWhen click is felt, note the maximum dial gauge reading
If in excess of this range, adjustment should be made according to the table below6Selection of shims The backlashes of the forward and reverse gears are as follows: