I have a 620 that I have no been able to use in winter for over 10 years. When ever it gets below freezing, the motor locks up and the starter can not turn it over. I have opened all the drain plugs to the crankcase and gear box oil to see if there is any water, and nothing. I took the fly wheel cover off to see if there was water pooled there and nothing. In the summer I run it a lot with a bush hog so you would think if any water is in the motor it would evaporate, but every winter for the last 10 years when I try to start it below freezing, the motor is locked right up and will not turn. Can someone give me an idea where I might look for pooled water that could be causing this?