I found that on one of the players i am repairing, i had problems with a couple of tracks not working. Machine was showing continual F in the tracks.
Here you can see the individual head gaps in the head construction. The amount of engineering that must have gone into this technology is really mind blowing.
You can see the far two gaps to the right don’t look as deep or sharp as the other 7 to the left. And you can also see the two wider gaps to the far left for analog playback.
Possibly this is head wear that has caused this gap deterioration. Unfortunately the user did play lots of analogue cassettes on it which may explain the wear.