http://archive2.avsforum.com/avs-vb/showthread.php?t=603378
This isn't exactly your set, but might be similar for removing front screen. Do not try to remove the back as the mirror will crash. Any servicing must be done through the front. You can also leave the protective screen off unless you need it as shown in the above thread. The url in my previous response will help with info on how to clean.
If you plan on keeping the set for a few years, an ISF calibration will make the set look better than new. It's a larger investment, but focus, overscan, greyscale, and dozens of other adjustments are made to produce a much better picture than what comes out of the box when new. These big old CRT boxes produce a great picture when set up correctly.