Suzuki DF25/DF30 Four Stroke Service Manual, Page 248Get this manual
10-24 LOWER UNIT Adjusting gear backlash To check the backlash, hold the driveshaft by hand, then gently rock forward gear back and forth by handGear backlash0.10 0.20 mm (0.004 0.008 in If backlash is larger than the specified, thickness of forward gear back-up shim must be increased If backlash is smaller, back-up shim thickness must be decreased
Checking and adjusting tooth contact pattern (Pinion and Forward gear) Check tooth contact pattern by using the following procedure: 1To assess tooth contact, apply light coat of Prussian Blue on the convex surface of forward gear