Tuning knob problem with Panasonic 19" TV

[atomictv]

Hi! I have a 1981 Panasonic CT-9010 that shows a grainy picture on channel 3, but when you twist the channel knob slightly to the right or left, picture becomes perfectly clear. Unfortunately, when you let go of the knob, it springs back to original position and picture goes noisy again. I've had quite a few TVs in the past that did this. Is there an easy fix for this problem, like some sort of calibration adjustment I can make inside?