Why arent my pancakes browning correctly?
You seem to be doing everything alright with the heat and pan. This sounds like a problem with the recipe. 

Add more milk (or yogurt, or whatever dairy you are using) - you need lactose for browning, so soy milk or enzymatically treated cow milk won't work. Also consider replacing part of the sugar with fructose, HFCS or glucose syrup, they brown somewhat better. Third, make sure they are not too sour. If this is a baking powder recipe, consider using only milk instead of any buttermilk or yogurt. If it is a baking soda recipe, add some more baking soda. If nothing else helps, you can even add a pinch of baking soda to a baking powder recipe, not for leavening but just for browning. 

The "makes a film and separates" part could disappear after changing the dairy and/or leavener. If it doesn't, make sure you are only lifting at the proper moment. The pancake will stick first, then become releasy, then burn. If it still sticks during the releasy part, reduce the heat (you should still get enough browning after the measures in the last paragraph). If that does not work either, the last step is to increase the egg. 

An alternative would be to find a better working recipe and follow it instead of adjusting yours. You might have to test a few until you find a winner.