ranger_co_1_75
On my grill the only locking position on the knobs is the off position. I have to push the knob in to turn the gas on, and then the knob stays at where ever I turn it to.

Just guessing
I don't quite understand what you mean by "lock". Most grills have knobs that you gently push and then turn clockwise and they remain where you stop turning. Maybe more details. Is it a new grill and did you assemble it or did it come already assembled?