After a month of fighting a rattle coming from the front part of my bike, I found it by accident. You may want to add this to your list of possibles. The fork lock on my 02X has a simple housing where the locking lug just turns up into the slot with the key. The housing for the lock is only held on by one screw upwards into the body of the frame. That screw was loose and rattling like my brain usually does. A little Loctite on that screw solved the problem.