I just got my first peak inside the 400ex i got today. I pulled the head to find the face of one of the intake valves lying on top of the piston. The piston was all banged up and black. I can get the thing to turn over so I suspect there is something wrong in the lower end as well. So far i'm looking at a new head and piston the bore looks ok to the eye but Istill need to mic it. what could be keeping the piston to not move up and down. When i try to bump it over with the starter it just moved down 2 inchs and then the starter just clicks. Looks like alot of money and parts ahead.