2000 Yamaha C115 starter will not engage flywheel

[<Ken>]

The pinion gear of the starter on my 2000 C115 will not entgage the flywheel on an average of about every fifth startup - I bought yamaha's service manual and it does not give me a clue. I have checked all connections including at the battery, the starter relay (both sides) and at the starter itself. My battery is fully charged. I have measured the voltage drop across the starter relay during cranking, and it is nominally 10-20 mv. I have removed the starter and then removed the pinion gear and inspected per the manual - and I can find nothing wrong except undue wear on the pinion gear teeth at the top where it has been hitting the bottom of the flywheel when it does not engage. When this happens, the pinion rises quickly up the starter shaft as it should, but instead of meshing properly with the flywheel, it slams into the bottom of the flywheel teeth and immediately falls back to its resting position on the starter shaft and spins until the starter switch is released. Sometimes it may take 10 normal startups before the starter acts up, but when it does, I may have to hit the starter two or three times before the pinion gear engages. Some of the teeth on the flywheel are starting to show undue wear on the bottom trailing edge - I believe this is where the pinion may be hanging up, but this starter has been doing this ever since it was brand new four years ago, not nearly as bad then as now - I am just mad at myself that I did not take care of this while it was under warranty. But I am determined to fix the problem, if I just new what to replace.
Any suggestions would be appreciated.

[<boats.net>]

1 out of 10 times would be hard to pinpoint problem if you know there is good voltage at starter then it is problably a starter problem. Starter dragging or bendix bad