VCR plays audio but no video

audio heads and video heads are seperate on VCR"s.....the video head might be extremely dirty and not able to pick up information from the tape..this requires major cleaning...manually..not with cleaning tapes....the guides might need to be re-adjusted..mechanically....or worst case is the little ferrite beads of the pick up heads on the video cylinder are no longer there, have broken off. in any case, the machine needs to be opened for service....cleaning the heads manually, you can do yourself with some paper such as note pad paper and acetone. acetone cleans very well, you spin the cylinder by hand while holding the acetone soaked paper against the heads. you might need to repeat this a few times with fresh paper depending on how much dirt comes off....good luck
silvio