Hi Ed,
An ESR meter is one of very pew pieces of gear I haven't acquired yet, and thanks for the tip. I'll try to get one as soon as budget permits. Looking at the service manual for my BR-S822U, there are 4 SMD electrolytics (.47 uF) that appear to deal with the headswitching on the flying PRE/REC board. I'm tempted to temporarily swap standard electros (all I have in stock) just to see what happens. These 4 electros appear to be in identical circuits, looks like they all supply DC control voltages to op amps inside the UPC2320GS chip on the flying board - but this is strictly a half-educated guess.
There's also a control signal that comes from the slip ring, but I admit that I've traditionally been a "belt and tire" guy and haven't studied the deeper areas of VCR electronics to know what this control signal should be or where it comes from. I should have all the equipment I need to troubleshoot - just need a bit more knowledge which I will study as time permits. But since the 4 electros in question are in identical circuits, maybe I can do a quick-and-dirty comparison of capacitance before pulling anything up. Here's a schematic of the flying preamp board:
www.barrys8trackrepair.com/PreBoard.html
Sorry it's not the clearest. Have a great Sunday!