I want to remove the knobs from my radio to install a face plate. I've never done this before on a mopar radio and do not want to break the knob or radio itself. There are two pieces, the round buttons that you turn for the radio power and tuning, and the collar pieces behind them that I assume control balance/fade. Are the round buttons simply pressed on? I haven't seen any threads on this so that is the reason for asking. Thanks.