Suzuki DF25/DF30 Four Stroke Service Manual, Page 242Get this manual
10-18 LOWER UNIT CHECKING PROPELLER SHAFT THRUST PLAY See the "GEARSSHIMMING AND ADJUSTMENTCHECKING PROPELLER SHAFT THRUST PLAY" section on page 1027
LEAKAGE CHECK Check for leakage of oil seal and O-ring when applying specified pressure inside of the gearcase09950-69511Oil leakage testerAir Pump