Black lines suddenly when playing back on Blaupunkt RTV-950

[jouse.]

Hey guys,

I was just in my finishing stadium with restoring some old VHS Tapes and I used my "favourite" of my Recorders, the Blaupunkt RTV-950 (Panasonic NV-FS200). It always worked well for years now, when suddenly I discovered some dynamic, black lines when playing back some tapes.

I have to admit, that I often opened the recorder and adjust the signal with a screwdriver, especially the screw for the "grain" when playing back VHS SP, if you know what I mean by that. I wanted to adjust and get the best signal possible for every single VHS Tape.

Could it be, that the head is damaged somehow, when producing lines like this? Or is the defect somewhere else?

I Uploaded a sample to demonstrate.

[jouse.]

No one? o.O