I'm following the article provided by Randall and authored by Clive Elsdon, called "Sidescreen Control Head". I have not gotten very far, and I've run into a problem where the countersunk screws on the back of the unit that hold the control head to the backing plate won't come loose. One of the screws has loosened, but I cannot get the other two screws to loosen. I'm using a good 9 inch screw driver with a very good tip that fits down into the countersink. The screw driver does slip out of the grove but I'm trying to minimize damaging the grove of those screws. Is it safe to use either Liquid Wrench on those screws, or some directed heat with an electric heat gun? I don't want to damage any thing inside the control head. Thanks!