it almost sounded like somebody was hammer drilling concrete or brick, it drove me nuts, and took me months to find the source of it,
my noise was caused by a loose eavestrough that was vibrating in the wind, would only happen with very strong gusts of wind,
you couldn't tell it was loose by looking at it, but after i secured it properly the noise disappeared and never has returned after a few years,
just something to check.....good luck
Mikey1, after having the poco come out and check the connection to the house, the noise is still there. It's a bit windy today, and now it sounds like its coming from just above the electrical connection. I also noticed that a gutter spike is missing at this area and I'm now thinking that you were right about it being the gutter. I'm going to pick up some gutter screws tomorrow and replace the missing one and see what happens. Thanks for the heads up.