[R-390] bad audio

[wli via R-390]

Symptom: severe audio distortion in all filter positions except 16kc.

Cause: loose PTO coupling! Looked fine externally, but upon close inspection, turning the KC knob, observed obvious slippage of the coupling to the PTO shaft. Solved by re-setting the PTO to 3455KC, and rotated the coupler so it mated exactly to the KC shaft locked at 7(-)0000. Retightened both Bristol screws on the coupler. Shimmed the rear of the PTO so that both shafts were aligned straight in both dimensions.

W. Li