Morba, you should have a go at this:
http://www.youtube.com/watch?v=JVRTnKUgARA&feature=plcp
Try it above and below the knee and even if it doesn't fix the main problem it will make it feel like you have a new knee in every other respect, which is always nice
. Just grab an inner tube and open it up and that works a treat.
If you found that you liked it you could experiment with other joints that may be causing you annoyance.
http://www.youtube.com/watch?v=JVRTnKUgARA&feature=plcp
Try it above and below the knee and even if it doesn't fix the main problem it will make it feel like you have a new knee in every other respect, which is always nice

If you found that you liked it you could experiment with other joints that may be causing you annoyance.