aluminum welded itself to the insert

6061, dry, because I didn't feel like dealing with coolant in a garage. Insert now has a cap of aluminum where the corner was. Part is galled. I assume this is on me.

Dry 6061 will do that. WD-40 or a proper aluminum fluid, sharper edge, don't linger. Pick the aluminum off the insert with a brass shim, not a steel screwdriver.