I had that problem with my Onkyo Integra 8700-A. That was years ago and as noted above, it was because I constantly switched between direct and stereo mode. I had it fixed by a local repair shop in Redwood City, CA. I do not hold Onkyo to the fire for my use situation.
Just to let you know, I'm a fan of some of your earlier work...
http://saloon.outlawaudio.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=20377&page=3