Hmmm not sure... doesn't look 'split' but can't see a metal piece on the flat side. Knob seems to fit snugly on the shaft
1. knob slides on fairly easily
2. knob turns shaft (i.e. regulates hob)
3. can turn shaft by hand (i.e. pliers not required)
ah, ok - will give it a go
checked 2x other knobs and neither had a metal piece - however a bit of cardboard has done the trick!
it's probably on the knob we use the most, so maybe it's a bit of extra wear-and-tear
I've swapped the knobs around so the 'damaged' knob is now on the least used hob