Check for metal filings in the transmission oil and do a gear vibration
analysis:

http://www.vibcons.com/vibration_data_collector.shtml

http://www.reliabilitydirect.com/vib...ts/vib_pen.htm

Here's some people that can do it for you:

http://www.thomasnet.com/products/vi...1870204-1.html

You can actually do the gear vibration analysis on the audio input port of
your pc.



"Ken" wrote in message
...
Here is the whole embarrassing story. A friend was at the helm, we
were motoring down the channel at 2600 RPM. I have a 3 cylinder Yanmar
engine. I was dealing with the sheets. I asked my friend to slow down.
He got confused between the transmission and the throttle. Instead of
cutting back the throttle, he threw the transmission from forward to
reverse! There was a terrible noise as you can imagine. My friend
immediately realized that he had made a mistake and shifted to
neutral. After that, the engine and transmission seemed to behave
normally but now I am not as confident as I was. So what do you think?
Will I need a new transmission? And what about the folding prop? Any
advice would be greatly appreciated.
Thanks,
Ken