I'm guessing you've already Googled the model number for replacement parts. I just did a generic Google for "range knobs 10mm" and it returned multiple results. Failing that, though, I also saw a "universal" replacement knob with multiple sizes of stem adaptors. This was a REAL quick search, though, and I'm guessing you should be able to find something which suits your specific needs.
Something like this for indent shape Imperial 36330 Imperial Knob Kit https://www.amazon.com/dp/B00HNQAM2K/ref=cm_sw_r_apan_glt_fabc_8N3F25DK53BJ4REDB8D0?_encoding=UTF8&psc=1
This many would work, but I was thinking fewer and slightly deeper just for simplicity.
I'm sure you can find them cheaper, but this is an example of what you need: https://www.amazon.com/Leviton-26115-W-Trimatron-Rotary-Devices/dp/B00332F0I4/ref=mp_s_a_1_14?dchild=1&keywords=light+dimmer+switch+rotary+knob&qid=1622332472&sr=8-14