The SV-Intercom-2S is shipped with 2 front plates, a horizontal and a vertical plate. I can't find a discription how to interchange the plates. Neither in the installation guide nor in a forum post. There is no obvious sign, how to remove the knobs to reach the nuts to loosen the plate. I don't want to damage the part by using to much force, pulling off the knobs. Could anybody gife me further instructions please?