A year+ later and I managed to Resurrect the CT1600 Sound Blaster Pro 2 model 1992 of the first post!

What made it possible was the arrival of a 1991 model SB Pro 2, which takes the 14,3 MHz 'OSC' oscillator signal from the ISA bus.
The broken model 1992 card has an on-card 14,3MHz oscillator instead, which I somehow suspected of being broken.
I measured out to where the working model 1991 routes the ISA bus OSC signal. The signal goes directly to CT1336 through a 80 Ohm resistor, which is called R8. Model 1992 also has this 80 Ohm R8 in a somewhat similar setup. So I lifted R8 on the broken card and connected it with a blue wire to the OSC signal of the adjacent ISA slot, model 1991 style. And behold the soundcard works flawless!

Now it may be neat to just replace the oscillator instead, but why is the max temperature for an oscillator just 260 degr.C? My solder iron works best on the 450 degr.C setting.

Past week I also managed to fix a DOA asus P2B revision 1.04 mainboard. The Mosfet closest to the DIMM slots (next to the 3 capacitors) did not make proper contact at the back of the Mosfet. It took me a while to notice this, as you could not really see it without pushing it.
Before the fix: No post with just blinking power and HDD LED, no Fans spinning up, no Beeps, and the 'Fault' pin of the VRM chip being 'high'.