Oven is 7 years old.

The knob used to turn the oven on has become quite "loose". When I say "loose", I mean that I can move the knob up and down and it moves pretty freely in all directions. Prior to tonight though, we've had no issues with the oven working, we've been careful to try and take it easy on the knob. Tonight though, when I shut the oven off, it didn't turn off. It was as if the oven was still set to 375 which was for my dinner. So, the gas would light to keep the heat up, shut off, light to keep heat up just like normal, but the knob was set to off.

Also, it's not the plastic piece with the temps on it that is loose, it's the metal control knob that's loose.

Is the looseness adjustable or just a part replacement - which part?

Thanks