hello, the winco mute key is next to the automatic, it is simply a tongue with contacts mechanically activated by the automatic its function is to cut the audio, when the turntable is in automatic function, and deactivates when the arm is raised, active when the arm supports the disc, you recognize it because the thin wires of the capsule arrive at that place, it is not very common to deteriorate, your problem could be in the capsule, to corroborate it, give it maximum volume and touch the terminals with your finger If the capsule exits, if it produces a loud hum, you will have to change the capsule because it does not work, with this test you are testing the amplifier stage, the hum when touching that place, tells you that it is working and the problem is the capsule, regards