[Wisha Haddan H3]

I don't care for the rock knob, but to each his own.

I don't know how to remove the knob, but I took a look at it just now. The top of the knob is a chrome piece (with the shift diagram) surrounded by shiny black trim. You can pry this off with your fingernails by pulling gently up under the trim. Comes off real easy.

Underneath is a metal piece in the center of the knob, about the size of a nickel. It's crossed by a shallow groove. I don't know if the groove is for a screwdriver (seems too shallow for that) but maybe that's how you remove the knob.

Btw, you can tighten the insert by bending the attachment pegs slightly out. Be careful ... they're not very strong.