Pitch Control Problem

Hey fellow Thereminists. I lended my Moog Etherwave Theremin to a friend and when I brought it back the pitch control seems to have no effect whatsoever. The dead zone is circa 10 centimeters from the Antenna (so pretty unplayable) and when I move my hand from the dead zone further from the antenna there´s just one constant tone playing that does not change at all by turning the Pitch knob. Only if I turn it to zero (full counterclockwise) it does very similar sound to the power on sound and then is just silent. Before that I could beautifully set up the radius, and have the dead zone wherever I wanted in the space.