I have a updated Hafler Dh 110 that when I touch the Bass tone knob I get a hum through the speaker and also the knob wiggles when moves up and down and side to side . All other knob are tight . ? Any thoughts
Ground is lifting, if the pot solders directly to the pc board look fir a broken track where 8it attaches to the board.
Also see if there is a nut loose on the front panel or sub panel under the knob. If held by a nut that is loose, the control may wobble, plus the body of the potentiometer may be screened only when the nut connects the body tightly to the chassis ground.