One thing to look for is a bad connection on the pole, kettle or at the weatherhead. Many utilities don’t get the connections weather tight and water will eventually get into the crimped or bolted connections and cause all kinds of intermittent corrosion related problems. Look carefully for bulged connectors or connectors that dry out quickly after a rain. That usually indicates heat from a corroded connection. Aluminum primaries are especially problematic. Usually a voltage recorder will show differential voltages leg to leg or leg to neutral / ground if one or more of the connectors are faulty.
Thanks for that advice Baldy. I haven’t heard from The Grid since they pulled the data recorder out a couple weeks ago. In the meantime I’ll check for any connections of interest with the binoculars. What you are saying makes a heck of a lot of sense since the distortion seems to always be at it lowest during stretches of time when we have no rain. During wet stretches of weather the distortion readings hit their highest recorded levels.