Phew, that’s quite some build up of dirt. Assuming the normal solutions (soft bristled brush, brushing in the direction of LP rotation ie back to front) do no good then perhaps very careful use of a bit of magic eraser attached to a toothpick may work. The ME got baked on crud off the top of my cantilever, albeit just at the stylus end.
Discussion of method is here
http://audiokarma.org/forums/index.php?threads/how-to-clean-your-cantilever-with-magic-eraser.723409...
Discussion of method is here
http://audiokarma.org/forums/index.php?threads/how-to-clean-your-cantilever-with-magic-eraser.723409...