digitalFAQ.com Forum - JVC HR-DVS3U squealing during playback?

Today I purchased a JVC HR-DVS3U unit at a local flea market. I don't know how long it has been there or how much use/weather it has put up with, but the top metal shell had a fair bit of scuffing on it.

When I got it home, I immediately tested the VHS playback. The first tape I tried worked like a charm, playing back with no issues. It looked and sounded fantastic. I then rewound that tape back to the start, ejected it, and put in another tape.

Immediately, a horrible, whining squeal began to come from the VCR, and the picture quickly became horrible, with tracking issues galore, and the audio scratchy and horrible. I opened the machine and couldn't find much visibly wrong, save for an odd spring which looked to me to be out of place or potentially caught on something, but also didn't have a hook on its end to connect to any other component, so I could be wrong.

I carefully tested another tape while the machine was open, and the same squealing occurred. It was very clearly only happening as a tape was running, and I'm fairly convinced that: A) The squealing is the sound of the tape itself being dragged - it sounds quite clearly like plastic being dragged or torn, and B) the sound originates from the audio head. I've listened closely, and I'm almost certain the squealing sound happens as the tape is pulled past the audio head. In the pictures, you'll see that the audio head is indeed quite disgusting, with some kind of grime on it. I'll definitely be cleaning that, but I don't know how the grime on the head would be causing this dragging, squealing issue.

Considering it played one tape fine, and immediately began to go on the fritz as I played a second tape, I think it's fair to believe this might be the result of a failed belt? I really hope this isn't something more complex, like failing caps or broken gears...

Youtube link to a video of the issue.