The other day I noticed that the AF knob was loose on my Elecraft K3. I got out the required alan wrench and proceeded to tighten up the two set screws that hold it in place. Unfortunately, I over tightened them and it cracked the knob badly. I emailed a parts request to Elecraft and was pleasantly surprised when the followed up letting me know that they would send me two replacement knobs for free! They said that they had changed the design of the knob for this exact problem and the new ones would prevent that. That's what I call great service!