The oval metallic-appearance oven knobs are made of plastic. Over time heat distorts then until they no longer grip properly. I purchased a replacement on-line via Amazon, only to discover on receipt that it was 29.97mm in length whereas what I need was 34.43mm.
No quibble from Amazon but none of the adverts for these things give the dimensions! Worse, it seems you can only get them if you buy the complete switch!
I do hate globalisation. :(
Rant over.