This is an area where an oil additive product might help. Some people have reported success with Xado EX120 in their juddering CVT gearboxes, and the company have a product listed for manual gearboxes which claims to address this noise/wear issue, although it sounds like the same stuff with different labels.
I am rather sceptical, but I have a client in the nano-tech industry and their work leads me to believe this stuff might actually work & be beneficial rather than snake oil in spite of the 'miracle-cure' literature.
"Revitalizant acts as a catalyst for rebuilding and repairing metal in areas of excessive thermal energy. It activates the absorption process of carbon through the surface layer which results in the formation of metal carbides. Revitalizant rebuilds metal at a molecular level, atom-by-atom. A new durable protective coating is formed with the help of carbides and metal particles. Because it has a self-regulating maximum thickness it does not cake. Diffusion of the protective layer into the metal results in an extra durable gradient coating with positive pressing stress forming along the entire treated surface in the final stage of Revitalization. The treated metal is now rebuilt and protected with diamond-like film of ceramic-metal"--
TG
Sources:
http://xado.co.uk/problems-noise-in-manual-transmission
