The metal shaft of the lock switch needs to be removed. To remove the shaft, drill in to the back of the switch body with a 5/16" drill bit.
Be sure to drill as centered on the body as possible and as straight as possible. Go slowly and be careful to stop drilling after you have gotten through the plastic body of the switch. To help avoid damaging the piston shaft pull it as far out as possible away from the area to be drilled.