I have 2 Panasonic AG-1980P VCRs that I purchased from ebay over the past couple of years. The video on both is darker with the TBCs on than off. But then it got worse. My favorite recently started getting so consistently dark with TBCs on that I shelved it until I had time to deal with it. But I recently noticed the other has unacceptable noise in a herringbone pattern. It might have had this noise as long as I've owned it, but since I was transferring old, bad tapes, I didn't notice. A recent transfer of a tape in good shape made me see it. So, I can't procrastinate any more. I need to figure this out.

I pulled the dark-with-TBC unit (Let's call it #1) off the shelf and checked it. Still very dark with TBCs on, but a scrambled mess with TBC off. Tried several tapes with the same results.

I manually cleaned the heads of both units. No improvement.

I read that the herringbone pattern on #2 might be do interference. I ran an extension cord from the basement. No improvement. (And no objectionable herringbone on #1 when it's plugged in using the same cord & outlet.)

I read power supply and capacitors are common problems. I took them apart and saw no bulging or leaking caps. I swapped power supplies in the two units. No improvement and no change. Unit #1 with the power supply from #2 had the same problems as it did with it's original power supply and vice vera. With the possible exception that Unit#1 with TBC off may be slightly less scrambled.

I read the head amp is another common problem. I swapped them, too. No real difference.

I don't have skills in electronics repair. I don't even own a soldering iron (yet?). But I love these machines. They are getting harder to find and the ones that are available have problems, too.

So, any recommendations as to what to try? Do you think I can rule out the power supply and head amp and need to look elsewhere?

Any help would be much appreciated. Thanks!