This became very clear to me a couple of months ago when LA8OKA's and my K2 were displayed side by side at our stand at Oslo Maker Faire. His is less than two years old, serial #7224, and they were similar except for the scratches in the faceplate of my tuning knob. If I am allowed to generalize from my knob only, it seems as if the faceplate had poor quality paint and has been replaced by a better quality version over the years.
Anyway I ordered a new one and paid the price which at present is $30.37 plus shipping. The difference is really striking and I feel like I have a new K2 now, well worth the price! The K2 now serves as my second rig, and I think it has many years of good service still to come.