Thanks,
The drive belts are due for a greasing.
I suspect the thermostat is open - since when I stop to let it cool it boils as one would suspect with coolant in the block.
The little tractor is approaching 3 years old. It's always run hot, but seems to be getting worse - maybe the grease. It's also due for an oil and filter change which may help, as well as an air filter.
Before I go to the dealer, I'll make sure all the maintenence is up to date and see what happens then.
Thanks, Joe