all but one of the four knobs were broken.

My folks were swtitching one knob around to controll all the burners. The repairman said the cooktop had been long retired and the only option was buying a new one. It's a great cooktop, though and it was a shame to ditch it for just because of knobs. Alas, right before we about to buy a new one, I discovered you guys. Halleluiah.