Remove the whole hood at one time... you will get short hood, cab, long hood.... after it is apart you can see how you could only remove one part.
Read this, has a disassembly for a USAT GP7, vers similar.
Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers
elmassian.com
BIG TIP get a screwdriver that is slender enough to get in the holes with clearance. make SURE the tip fits the screw tightly. If you don't do this, you can strip the screwhead and never get the shell off.
After it is apart, a drop of plastic compatible oil on the screw threads will help avoid problems. Do NOT tighten the screws too much, they strip in the plastc EASILY.
Greg