If it were me , I would buy a larger piece of cork knob from the hardware store, file down the end to fit into the existing cork butt end and then glue it in. Done fixed. I wouldn't get a custom piece made to fit. This is an easy do-it-yourself fix or you can find a round rubber leg foot, and just slide it over the existing butt end. Cheap, effective and easy.
"Practice, practice and more practice, and if you think you're good practice some more". circa 2006, Cadman