Mercury Force 9.9, 15HP Outboards Service Manual, Page 174Get this manual
11 Inspect lower gear housing Measure inner diameter of front gear bearing Carefu lly check inside of bore for cracks, corrosion and burrsRemove burrsSuperficial corrosion may be permissible if not on sealing surfaceCracked housings must be replaced 12Inspect propeller shaft bearing Replace if worn Propeller shaft bearing (A) can only be replaced by replaci ng housing