So what is the "Panasonic power supply issue"?

[Ed in Tx]

What's the tape path look like at the guide just after the AC head? I've seen the vertical forward-back tilt or "zenith" of the AC head. or a worn pinch roller, cause tape skew.

If you go messing with the entry and exit rollers you will probably need an oscilloscope hooked to the head amp RF-out to do an alignment assuming you have a known good tape. Put a small mark with a felt tipped marker on the shiny metal part on top of each roller assy just in case, so you can put them back where they were.