plastic knob missing

[waxahachie]

Hello, some people know I have on Virus Classic Desktop, I bought it on Ebay few weeks a go with one plastic knob is missing, I bought one in a electronic store but is different, I contacted already a few different places for try to buy one replacement used or new or even from a different Virus (I think are all the same size and form) but nobody reply back to me, the question is if some one have one for sale or where I can order it, please send a private.
Thank you.