Cambridge Azur 851A Problem! Help!!

I just sold my 851 and the buyer sent me a video of the toggle on/off switch on the back is in the "ON" position and won't stay in the "Off" position. B ut it is powered "ON". I never had a problem with it before. What could it be??It doesn't make sense.. I doesn't have any speakers hooked up to it because he says" He's in between speakers right now.???? 


Where can I find (buy) replacement switch?  Mine now has the same problem (can’t turn it completely off).

Got it, ordered two switches just in case I need another one down the road.  I always turn the unit off after using it, so the switch gets used.