Jack is right on the money. I just sent in my M390 Military because of a concern that I had with the linerlock and figured that, if they determined the same problem that I did, they could just replace the liner within the CF scale but no such luck. CS explained that even the most minor of changes in CQI of the liner, or the scale, would not permit it to just replace the one on the knife. Of course, my issue was with the liner and not the blade but I'd say it'd be the same for any part of a Spyderco knife.
It's a shame since it wouldn't have bothered me at all if they had put that M390 blade on a G10 handle....:grumpy: