A friend of mine with a '00 Lude had a 5th gear grind issue. Turned out the shift fork was bent. This may not be the same problem you're having though.

Check your MC, lines, and calipers for any potential leaks. Start with a brake bleed and flush out all the old fluid and make sure new stuff is getting to all four corners (grab a friend to help you do this). It may be as simple as some air in the lines or a leak. If neither of these solve the problem, you may want to consider swapping out the MC for a new unit.