They should both be straight blade heads, there is a phillips screw you should NOT remove. Get a good purchase on the head and then apply sudden force and they should break loose. If not try a socket driver with a properly sized bit. Best of luck. Rick.
ANYBODY that intends to work on an outboard motor needs one of those impact screwdrivers. The bit rotates when you whack it with a hammer. The hammer blow also keeps the bit from jumping out of the slot. Works both ways, taking screws out and putting them back in. The tool will have those tight screws out before you even have time to think about it.
I agree with what was said about the impact drivers I have one and it works great. In a pinch I also used vise grip pliers locked onto the handle of a large bladed screwdriver.
