Our left rear burner knob will not turn. We took the cover of all the burners off, nothing is jammed or stuck. This burner is not used much but we needed it for T-giving dinner prep, so of course thats when it failed 
Called KA to see if under warranty, but they said i would have to pay a service tech to come look at it and tell me if it was under warranty…huh?
we thought we would just replace the control mechanism ourselves, but are not sure which part to buy. This range was purchased in Aug 2012, double oven, gas.
Any help or suggestion are very much appreciated.
Thanks, 
Lisa