I gave up on the torch and just put my za50 case in the oven, set it to preheat to 375⁰ and let it preheat with the case to avoid rapid temperature changes. No issues with paint or oil baking off, just make sure it's really clean before putting it in there. Took a few rounds of heating and smacking on wood, little bits of movement each time, but eventually they came out. (edited)