One possibility is fake owls and hawk silhouettes to scare them off.
If they're actually going after bugs in the siding, you might do something to get rid of the bugs. Then, there'd be no more reason for the birds to peck.

Use caution as Woodpeckers are protected by the federal government. There are many scare tactics as mentioned above. You may also try hanging some mylar tape near where they are pecking or drumming. They become scared of the shiny reflections produced by the mylar tape. Also there are some electronic devices out now, however, the effictiveness has not been proven.

Good Luck,

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i had the same problem all u do is put electric wires around the trees it likes harmless lee the bird get a small shock but not alot to kill it i ever had a problem since