The rear section of the lens is built into the EX EE. Mind you, I have not seen one in decades! But there will be a lot of work involved, I believe, in taking this section out of the camera. You may want to go onto Ebay or online shops that specialize in repair manuals.
I suspect that it would be easier to pop the top off of the camera and remove the prism to get to the dirty screen. You will also get a look at the prism. I have done this, ie removing the top plate, prism, and focussing screen, on a Kodak Retina Reflex S. It was very easy on that camera and took about 45 minutes to replace the pentaprism. BUT this is going pretty deep into a camera, and unless you are good at taking them apart (and putting them back together) or just want a learning experience, I would advise against you doing it. If you really like the camera, wait until it needs a CLA and have the pro's do it.
The Canon EX EE was aimed at the amateur market and had a limited number of lenses available, a 35mm, 50mm, 95mm, and 135mm. The lenses for the EX EE did not work on other Canon SLR's as they replaced the front section of the standard EX EE 50mm F1.8. It was priced almost the same as the FT Ql which took a full line of lenses. The EX EE did not sell as well as its bigger brothers. Unless you really like this camera, or it has sentimental value, the price of a professional CLA is probably more than the camera is worth. Of course I have spent more money having several cameras professionally cleaned and repaired than they were worth just because I liked them.
