One of my intake valves keeps tightening up on my 02. I know this is a problem so should I replace just the one valve or replace both? Lap it in?? I heard this is a no no? Just put a new one in and run it, or do I need to have the seat cut? I have about 40-50 hours on it I was also thinking of putting a new set of rings in while the head was off. I'm new to this four stroke top end stuff so any helpful tips are appreciated.