Great info! Thanks to all. I seem to have improperly defined the EQ taps as bias. I apologise for any confusion. They indeed are transformer EQ taps. One row for the bass and another for the mid-range. And are ID’ed left to right as -3db 0db +3db. And are also color coded black white red. The previous owner only supplied one jumper per speaker. So I’m assuming I need to source another set to adjust both bass and mid on each.
The overheated resistors in question are 7.5ohm 20w sand resistors. Which are tightly bundled 4 square and board mounted in each interface. For whatever reason the 2 mounted on the inside of the board seem to have run hotter than the outside facing pair. The 4 pretty well roasted the fiberglass and definitely compromised all solder joints in that area. After removing and sanding all 8 resistors ends. It now seems that only 2 of 8 are actually out of spec electrically. But all are pretty well roasted. All of which I suspect led to higher resistance solder joints along with higher required drive levels. And mucho heating. Unfortunately, I’m clueless as to what the previous owner employed for amps. But I suspect they were sizeable and humping.
I’m definitely going to disconnect the brilliance pots. As I suspect the improvement in upper reproduction may be substantial. Plus I suspect the pots have seen better days and are polluted via the rear vents. Thanks so much for the great data on those resistors. I’ll get on the research and get them in the mail.
I have pics which are no doubt worth thousands of words. But presently it seems due to handheld device issues. I’m incapable of uploading at this time. I’ll try later when the desktop is near.
I’ll get the parts orders underway and let you know the progress. Hopefully the panels are still unburnt and in good shape. The socks are still tight so they should have only been externally exposed to microdust and humidity.
Again many thanks for all of the assistance.