If you do feel adventurous, it's not a difficult job. You start by removing the retaining ring which holds the round faceplate around the lens. Once the ring is removed, you simply pop out the faceplate. Behind the faceplate is the light meter baffle ring, this should pop out too.
Once these are removed, you need to remove the lens elements. You need a lens spanner with narrow points, as there isn't much room to grasp the notches. Once the element group is removed, you'll need a set of soft nose pliers and your lens spanner to disassemble the elements.
When the front group is removed, you can remove the three screws which hold the aperture selector ring in place. After remove the screws and pulling off the ring and it's holder, you'll see the round brass plate which covers the shutter assembly. Remove the two screws which hold the meter cell, and then the three screws which hold on the brass plate.
If you are looking at the camera from the bottom side (top facing away from you), you'll see the self timer mechanism on the right, and the shutter mechanism on the left. On the left is also the electromagnetic coil which regulates the shutter speed. There are two linkages nearby which operate the shutter. If you cock the shutter, press your finger on the linkage below the coil nearest the shutter, and then press the shutter button, the shutter will stay open, and allow you to clean the inside of the rear element.
The two pivot points on the linkages nearest the shutter should be lubricated. The lubricant on these pivots dries out in time, which usually results in overexposed images.
Putting the camera back together is the reverse of the above, though you have to line up a pin on the aperture selector ring with the notch that receives it. It is a simple process.