Check switched pot's from this manufacturer/model. Back pins for the on/off (on three out of four) were tied to the wiper on the inside. Had you installed these without checking the on/off - and it was tied into an audio circuit - you would have nightmares trying to figure out where the problem was. As you change the pot, the on-off switch resistance would be changing some other part of the circuit but it might be hard to trace to the back pins. Seller refunded, No hassle.