There's the standard 2 x2 layout of burners, the control knobs run up the right hand side. I don't know the make or model, it's built in to the worktop & was already there before we moved in. Possibly before we were born, if the rest of the place is anything to go by.
Normally, they park at the 9 o'clock position, you press down and turn (CCW) to 6 for max (and to ignite). Min is roughly at 4.
Here's the problem: the one at the back (controls rear right) has been giving problems. For a few days it would turn without pressing. Now it won't turn at all.
Taking off the plastic knobs, I see that the D-section rod sits lower By perhaps 3 or 4 mm) than the other three which are all working OK. I also see that the mechanism on this one is well mucky and the others aren't. I suspect Mrs Hog's Eyetie coffee machine (the octagonal screw- apart type, like a Bialetti) has spilled onto it and gunked it up.
Any ideas other than dousing it in WD40 and/or writhing at it with mole grips?
Yes, I'll probably turn off the master valve before doing anything. If I forget, wave as I pass over.