Markoz wrote on Nov 7^th, 2016 at 12:39am:

I tried everything I could think of, but I couldn't silence it. That included moving the 3 MKR Switches (the 2 on the Pedestal, one labelled as MKR 2, and the 1 near the Engineers panel). I even added a 2D BoeingGeneric!Audio panel (used in the default B747) to the 707, but the MKR button remained green no matter how many times I pressed it.

That's going the extra mile   ;)  Thanks for looking into it.   I don't really mind it all that much when landing, but it can be distracting on takeoff when you've already got a lot to deal with.