Doing some minor repairs on my vp-1000 and found this.

https://s1.postimg.org/xaxv92yf3/IMG_2606.jpg
https://s1.postimg.org/q94j0mk73/IMG_2607.jpg

I'm so very tempted to play with them, but I'll leave them be.

You'll find those same adjustments on every player. They are just easier to access on this player than on others. Unless you've got an incredibly steady hand, an oscilloscope, test discs and service manual, it's probably best to leave well enough alone.

I've found that not all of those potentiometers require an oscilloscope to adjust, actually -- most seem to just be voltage values, according to my VP-1000 service manual. Had to play with them to get my Frankenstein'd unit up and running, but now that they're set, no trouble.

I do agree, though: don't mess with them unless necessary. However, if you do need to, let me know, as I have the service manual in a PDF form.