I shall clarify that it's not the repairing is difficult, but the process to find the right parts. My surface burner from Magic Chef is over 20 years old abut works very well. However, the knobs are broken. It took me many hours searching online and visiting multiple appliance stores to finally find the correct one here. So, I want to share my experience here. My old original knobs are these: https://www.partselect.com/PS2091459-Whirlpool-7711P150-60-Surface-Burner-Knob.htm?SourceCode=3&SearchTerm=PS2091459, and they can be perfectly replaced by these: https://www.partselect.com/PS2007393-Whirlpool-12500060-Set-of-Five-Surface-Burner-Knobs.htm?SourceCode=3&SearchTerm=7711P337-60.
It was very simple: I pulled off the old knobs and installed the new ones. All I had to do to install the new ones was to press them into place. They give my stovetop a whole new look!