I don’t know if this question is so simple as to be hideously embarrassing…
The rubber ring-seal-washer-thingies under the knobs on my hob have perished. Are these standard, buy-them-off-the-peg-in-B&Q sort of things, are are they very specialised, specific-to-the-model-order-off-the-internet sort of things?
And if I do have order it, what’s the technical name of them?