One of the fans on my computer has been out for a while now. I've been compensating by placing a large box fan inbehind my CPU in order to cool it down. I tried moving it manually, but there seems to be some resistance. My guess is that it is because of massive dust build up. In order to disassemble the fan to get at the problem, I must unscrew four screws.

I managed to get two of the four screws out (yellow arrows point to them) but can't get the other two out. (marked in green) There is a metal piece (marked in red) and the smaller fan (marked in blue). Both are in the way, so it is not possible for me to unscrew them with a screwdriver.

I managed to get past two other screws when taking another computer piece off by placing the bit into the screw, then using needle nose plyers to twist it around 3/4's of a turn, then unscrewed it the rest of the way by hand, which really, really hurt my fingers. I do not believe this can be done with these two screws, however.

Any ideas?