Some of the Harmony pick guards we receive are so badly cupped as to be unusable. This page describes a way to flatten cupped pick guards.
Preheat oven to 220 degrees f.
Put the pick guard between two scraps of 3/4 cabinet grade veneer core plywood. Place the plywood and pick guard in the oven with the pick guard between the two scraps. Do not put the clamps in the oven.
Heat for one hour.
Remove the plywood scraps and clamp immediately with at least two C-clamps. The clamps shown here are Jorgensen #104 clamps capable of 4000 lbs/square inch pressure.
This results in a perfectly flat pick guard.