This is a little off topic, but what the heck.
I have an older (1961) Evinrude Lark outboard which isn't pumping well. I've had the impeller and thermostat replaced, but it still isn't pumping well. It spits a little water at high rpms, but nothing at idle.
Two people have told me that a mud dauber or other insect probably made a nest in one of the water lines. If this is correct, or there is some other type of internal blockage, short of taking the motor apart is there a good way to clear out the blockage?