Phew you had me thinking. I just read the 650 service manual and it is correct , even in its pictures. What I would do if I were a 400 owner and I was taking my machine in for service is, I would ask the service dept if they were familiar with the service manual error in regards to this service. That way you could go from there depending on there answer. If they insist that theres no error then I would pull my machine and head else where. Or ask to see if they have an updated manual? Tell them the version you have has errors in it in regards to component identification.