I hope you have tips to help me troubleshoot my brake lights.  '84 Westy
Wolfsburg.

Symptom: No brake lights.  No brake warning light, either.

A local VW shop worked on this a few weeks ago.  They checked the brake
light switches and found no problem there.  They believe the problem was
due to a backup warning system that had been spliced into the left
taillight wires (ground wire and reverse light wire), so they removed
the spliced-in wires, leaving the original wires chewed up by the
cheap-o splices.

The reverse lights, taillights, turn signals, and side markers all are
working fine, but I went ahead and repaired the chewed-up wires (solder
and heat shrink), and the reverse still lights work fine.  I don't think
it's a problem with that ground wire, which serves the whole assembly.

With the brake pedal held down by a piece of wood, there's no power on
the brake light wire at the left or right taillight assembly.

Fuse #8 is intact and has power on both sides.

That fuse originally served the interior lights and cigarette lighter.
The GoWesty aux battery kit removed those from the fuse, leaving just
the "stop lights" (as they're called in the Owner's Manual).  I
installed that kit years ago, and the brake lights were working until
recently.

I have not checked the brake light switches myself.  I think they'd have
to BOTH fail to get no brake lights AND no brake warning light, right?
Is it hard to get in there and get a voltmeter on the brake light
switches?  I took a peek, but I haven't removed the instrument cluster yet.

Thanks for your advice.