The VCR uses two different types of heads; the rotary head which handles the video signal and a stationary head very much like any magnetic tape recorder. This latter head may be contaminated with tape residue.
If you are feeling adventurous, you could open the case, examine the path of the tape and look for a small head, curved on the tape side where it contacts the head, use a cotton swab dampened with a bit of naptha (lighter fluid) and scrub the tape contact surface with it. Use a clean swab to remove any naptha still coating the surface, give it a half-hour or more to dry any remaining naptha you've missed.
If that made no difference, either the head alignment has drifted or the circuit handling the signal from it has failed. The would mean 'time for a tech.'